Tak-MAK, Squak-MAK and Flak-MAK
By Alan Marshall
I was fresh out of Remington 700s - right hand, short action 700s to be more specific. Mine are the superior left hand versions, which are great unless you're right handed, as my boys are. So doing what any dad would do, I bought two right hand, short action Remington 700s for my boys. This will be the story of the first one. My goal was to make a switch barrel rifle so I could start out with a light recoiling caliber and then work up to a .308. I found a barreled action with a heavy barrel .204 and thought that it would be a good starting point. I found out why it was for sale after I shot it, but I'll get back to that in a moment. I already had a spare 700 .223 sporter weight barrel sitting in the corner and Mr. Del contributed a couple of .308 Heavy Barrel take-offs to the cause. I purchased a used sporter weight 7-08 barrel and was ready to roll.
This is a MAK XC tube gun kit, in its Tak-MAK switch barrel format. Inside the aluminum receiver tube is a Remington 700 short action with a factory .308 barrel cut down to 20 inches. The tube has been modified to retain the factory safety. On top resides a Leupold 6.5-20X scope in Burris rings, along with a Harris bipod, Magpul MIAD grip, AR-15 A1 stock, Alpha Industries 10 round magazine and 'Big Head' aft cap screws. It's in the company of a ghillie cover, Mildot Master, box of TAP ammo and an Eberlestock Gunslinger backpack with integral rifle pouch.
204
I started out by bedding the 26" .204 barreled action into a McMillan stock. With great expectations I set up some orange dots at 100 yards, grabbed four boxes of factory ammo and got the ball rolling with a 3.89" group with the 40 grain Accutip-V ammo. That's right - the decimal point is after the '3', not before it. But I wasn't discouraged - many of my projects start out like this. I tried some 40 grain Vmax ammo and shot a much improved 3.86" group. There's progress - at this rate, I'm just 120 groups away from the quarter inch club. Plan B - let's try some 32 grain bullets. The 32 grain Ballistic Silvertips shot 1.03" for three shots. The 32 Vmax was the velocity king at 4062 fps and produced a three-shot group that was one inch even. The second group was .88" with two shots touching. Still not too good and can someone tell my why the Remington 1:12 twist barrel won't shoot the Remington 40 grainers? I took a peek at the crown (my previous article not withstanding) under a 10x stereo microscope and didn't see any obvious problems, although I did notice that one of the lands had a gouge in it.
I decided to chop a couple inches off the muzzle to get back to "good" lands and maybe find a better, tighter section of barrel. I'm happy to say that the accuracy did improve with the shortened barrel. The downside was that although mama's little baby loves shortnin', the speedy little bullets didn't care much for it, losing about 100 fps. The 40 grain Accutips dropped from 3690 fps to 3615 fps. The 32 grain Ballistic Silvertips dropped from 3960 to 3855. The 40 grain VMax bullets dropped from 3735 fps to 3625 fps. I wondered about headspace so I got out the Stoney Point Head 'N Shoulders headspace gauge and checked some factory ammo. The unfired Accutip-V, Ballistic SilverTip and Hornady VMax all ran 3.555 to 3.557" long. By comparison the fired cases ran 3.559". No red flags there. The fired case mouth's ID was .206". Also OK to me. The cases resized in my RCBS dies measured 3.557" with the case mouth ID of .201".
I checked the jam length and found that I would have to load the 32 Vmax bullets out to 2.451" COAL to jam the bullets into the lands. Unfortunately, at that length the neck barely holds the bullet. I played around with different bullets, powders and cartridge overall lengths (COAL) and had success with Sierra 39 grain Blitzkings, in Winchester brass, BR4 primers, 28.0 grains of W748, loaded to 2.296" COAL. Those gave me a .15" three shot group at 3600 fps. Look out ground attack and airborne squirrels, the Squak-MAK is ready. A 'squak', by the way, is what my former boss, Bob Murphy, called squirrels. With Hornady brass, BR4 primers, 29.5 grains of W748 and 32 grain Vmax bullets loaded to 2.298" I fired a .44" group at a muzzle velocity of 3965 fps. These were with a recoil lug .189" thick.
I fired four types of bullets into 10% nominal ballistic gelatin at close range (25 yds). The 32 Vmax at 4062 fps produced a 5 inch spherical explosion of copper and lead fragments. OK- it wasn't really an explosion but a varmint would be in no position to argue the point. I've heard that if a jackrabbit gets hit with one of these, it looks like he ate a grenade. The 32 grain Ballistic Silvertip at 3962 fps penetrated 10.5 inches, with the first 6 inches containing a grapefruit size explosion followed by the copper base pushing thru an additional 4 inches. The 40 grain Accutip-V went 7.5 inches at 3691 fps. The 40 grain Vmax penetrated 6 inches at 3735 fps and also blew all the way through a vicious 'chuck intending to do me harm. These gel shots were fired before I shortened the barrel.
Remington 700 take-off barrels, recoil lug shims and recoil lug/spacers. 'Squak' barrels on top and 'Tac' barrels on the bottom.
Since I wanted to make this rifle into a switch barrel I did my best to remove the barrel. I had the barrel vise and I had an action wrench. No dice. I contacted Remington and was informed that "most of the 700 barrels are Loctited on with red Loctite and they are installed with about 120 foot pounds of torque." I tried heating the action to soften the Loctite. No dice. So I sacrificed the recoil lug. I drilled .16" diameter holes in the lug from 9 o'clock up to 12 o'clock and around to 3 o'clock. Then I connected the dots with a MotoTool cut off wheel. Then, using a screwdriver and hammer I broke loose both thin arcs remaining, leaving only the bottom half of the lug pinched between the action face and the barrel shoulder. Using a pin punch and hammer I tapped the lug free. Even with the recoil lug removed, the barrel still wouldn't come out. So I heated it up once more and was finally able to turn it off once the Loctite softened. The lug that I removed measured .189" so I replaced it with a lug of the same thickness. You can buy used lugs for about $15, but they come in various thicknesses from about .176" to .189". I polish and thin out the too-thick ones, if they're close to what I need, on wet-dry paper. A surface grinder would be pretty handy for this too. You can also make shims from the steel shim stock that Brownells sells. It comes in various thicknesses.
By Alan Marshall
I was fresh out of Remington 700s - right hand, short action 700s to be more specific. Mine are the superior left hand versions, which are great unless you're right handed, as my boys are. So doing what any dad would do, I bought two right hand, short action Remington 700s for my boys. This will be the story of the first one. My goal was to make a switch barrel rifle so I could start out with a light recoiling caliber and then work up to a .308. I found a barreled action with a heavy barrel .204 and thought that it would be a good starting point. I found out why it was for sale after I shot it, but I'll get back to that in a moment. I already had a spare 700 .223 sporter weight barrel sitting in the corner and Mr. Del contributed a couple of .308 Heavy Barrel take-offs to the cause. I purchased a used sporter weight 7-08 barrel and was ready to roll.
This is a MAK XC tube gun kit, in its Tak-MAK switch barrel format. Inside the aluminum receiver tube is a Remington 700 short action with a factory .308 barrel cut down to 20 inches. The tube has been modified to retain the factory safety. On top resides a Leupold 6.5-20X scope in Burris rings, along with a Harris bipod, Magpul MIAD grip, AR-15 A1 stock, Alpha Industries 10 round magazine and 'Big Head' aft cap screws. It's in the company of a ghillie cover, Mildot Master, box of TAP ammo and an Eberlestock Gunslinger backpack with integral rifle pouch.
204
I started out by bedding the 26" .204 barreled action into a McMillan stock. With great expectations I set up some orange dots at 100 yards, grabbed four boxes of factory ammo and got the ball rolling with a 3.89" group with the 40 grain Accutip-V ammo. That's right - the decimal point is after the '3', not before it. But I wasn't discouraged - many of my projects start out like this. I tried some 40 grain Vmax ammo and shot a much improved 3.86" group. There's progress - at this rate, I'm just 120 groups away from the quarter inch club. Plan B - let's try some 32 grain bullets. The 32 grain Ballistic Silvertips shot 1.03" for three shots. The 32 Vmax was the velocity king at 4062 fps and produced a three-shot group that was one inch even. The second group was .88" with two shots touching. Still not too good and can someone tell my why the Remington 1:12 twist barrel won't shoot the Remington 40 grainers? I took a peek at the crown (my previous article not withstanding) under a 10x stereo microscope and didn't see any obvious problems, although I did notice that one of the lands had a gouge in it.
I decided to chop a couple inches off the muzzle to get back to "good" lands and maybe find a better, tighter section of barrel. I'm happy to say that the accuracy did improve with the shortened barrel. The downside was that although mama's little baby loves shortnin', the speedy little bullets didn't care much for it, losing about 100 fps. The 40 grain Accutips dropped from 3690 fps to 3615 fps. The 32 grain Ballistic Silvertips dropped from 3960 to 3855. The 40 grain VMax bullets dropped from 3735 fps to 3625 fps. I wondered about headspace so I got out the Stoney Point Head 'N Shoulders headspace gauge and checked some factory ammo. The unfired Accutip-V, Ballistic SilverTip and Hornady VMax all ran 3.555 to 3.557" long. By comparison the fired cases ran 3.559". No red flags there. The fired case mouth's ID was .206". Also OK to me. The cases resized in my RCBS dies measured 3.557" with the case mouth ID of .201".
I checked the jam length and found that I would have to load the 32 Vmax bullets out to 2.451" COAL to jam the bullets into the lands. Unfortunately, at that length the neck barely holds the bullet. I played around with different bullets, powders and cartridge overall lengths (COAL) and had success with Sierra 39 grain Blitzkings, in Winchester brass, BR4 primers, 28.0 grains of W748, loaded to 2.296" COAL. Those gave me a .15" three shot group at 3600 fps. Look out ground attack and airborne squirrels, the Squak-MAK is ready. A 'squak', by the way, is what my former boss, Bob Murphy, called squirrels. With Hornady brass, BR4 primers, 29.5 grains of W748 and 32 grain Vmax bullets loaded to 2.298" I fired a .44" group at a muzzle velocity of 3965 fps. These were with a recoil lug .189" thick.
I fired four types of bullets into 10% nominal ballistic gelatin at close range (25 yds). The 32 Vmax at 4062 fps produced a 5 inch spherical explosion of copper and lead fragments. OK- it wasn't really an explosion but a varmint would be in no position to argue the point. I've heard that if a jackrabbit gets hit with one of these, it looks like he ate a grenade. The 32 grain Ballistic Silvertip at 3962 fps penetrated 10.5 inches, with the first 6 inches containing a grapefruit size explosion followed by the copper base pushing thru an additional 4 inches. The 40 grain Accutip-V went 7.5 inches at 3691 fps. The 40 grain Vmax penetrated 6 inches at 3735 fps and also blew all the way through a vicious 'chuck intending to do me harm. These gel shots were fired before I shortened the barrel.
Remington 700 take-off barrels, recoil lug shims and recoil lug/spacers. 'Squak' barrels on top and 'Tac' barrels on the bottom.
Since I wanted to make this rifle into a switch barrel I did my best to remove the barrel. I had the barrel vise and I had an action wrench. No dice. I contacted Remington and was informed that "most of the 700 barrels are Loctited on with red Loctite and they are installed with about 120 foot pounds of torque." I tried heating the action to soften the Loctite. No dice. So I sacrificed the recoil lug. I drilled .16" diameter holes in the lug from 9 o'clock up to 12 o'clock and around to 3 o'clock. Then I connected the dots with a MotoTool cut off wheel. Then, using a screwdriver and hammer I broke loose both thin arcs remaining, leaving only the bottom half of the lug pinched between the action face and the barrel shoulder. Using a pin punch and hammer I tapped the lug free. Even with the recoil lug removed, the barrel still wouldn't come out. So I heated it up once more and was finally able to turn it off once the Loctite softened. The lug that I removed measured .189" so I replaced it with a lug of the same thickness. You can buy used lugs for about $15, but they come in various thicknesses from about .176" to .189". I polish and thin out the too-thick ones, if they're close to what I need, on wet-dry paper. A surface grinder would be pretty handy for this too. You can also make shims from the steel shim stock that Brownells sells. It comes in various thicknesses.
Tak-MAK, Squak-MAK and Flak-MAK - 2
223
For a more universal and easy to find caliber choice I have a 24" .223 sporter barrel that was a gift from S. Pence. I made two recoil lug discs/spacers on the lathe. They were .187" and .189" thick, 1.30" OD and 1.065" ID. With the .187" lug the bolt wouldn't close so I fitted the .189" lug in place and it worked just fine. I recrowned the barrel and shot a few firelapping rounds down the barrel to smooth everything out and, yes detractors, increase the jam length about 15 thousandths. On the factory load side, the Black Hills 40 grain Ballistic Tip load left the barrel at 3470 fps, with a group of .5 MOA. With handloads, I had good luck with 24.5 grains of AA2495 in Nosler brass, BR4 primers and 55 grain Berger bullets. With a COAL of 2.317", I got 2960 fps and 3 shot groups averaging .6 MOA. The 52 grain Sierra Matchkings, also pushed by AA2495, are averaging .4 MOA. I feed the .223s using the AI 10 round plastic magazine. It has plenty of room fore and aft inside the magazine to load your cartridges out to an overall length of 2.55" (compared to normal AR-15 magazine length of 2.26").
Extra Bolt (top), wood barrel vise spacers and Surgeon action wrench tool for changing barrels (middle left), Borka adjustable torque wrench(center), nylon single round loading block (middle right), AI 5 round .308 magazine (bottom left), Alpha Industries 10 round .308 magazine (bottom middle) and AI 10 round .223 magazine (bottom right)
7-08
I purchased a used take-off 7-08 barrel for $45. It was blued, 22 inches long and .66" OD at the muzzle. I recrowned it on the lathe and broke the crown's edge with a .45 FMJ bullet smeared with 220 and then 320 grit lapping compound. I threaded it to accept a Ross muzzle brake threaded 5/8-24. The brake is Stainless Steel that I sand blasted with a Campbell Hausfeld sand blaster using play sand strained thru a screen. I wanted the hole to be .030"over bullet diameter so Ross, the brake maker, drilled it out to .314". The brake has 3 chambers with 3 top ports and 3 ports on each side. It cost $40 shipped and was money well spent. I made a spacer .080" thick to time the brake top ports to be top dead center.
I found that 7-08 cartridges won't feed through a 700 that has feed lips intended to feed .204 cartridges. I had read that this would happen but figured I would find out firsthand before I moved to the next step in the project - converting the rifle from a drop floorplate magazine to the detachable AICS magazines. In the mean time, I just single loaded my handloads. I forgot to mention that I have a second bolt to handle the 7-08 and .308 cartridges. Speaking of bolts, you may want to paint barrels and the appropriate bolt that works with them the same color. That is, the 7-08 and .308 barrel could be painted OD green to go with a .462 bolt that is also painted OD. The .204 and .223 barrels could be painted black to go with a .378 bolt that is painted black. If the colors match, you're good to go. That might prevent you from bringing your rifle to the bench with a .223 bolt and a 7-08 barrel. Ask me how I know this.
The jam length for this barrel is around 2.78" for the 7mm Sierra Matchkings in 150 grain and 168 grain weights. That's a pleasant surprise since that COAL is shorter than magazine length. Factory R7M081 ammo loaded with 140 grain PSP bullets averaged 2750 fps and yielded 2 MOA groups. I pulled the bullets and weighed the powder. I loaded some 'Mexican Match' ammo by dropping 2 grains of the powder (from 45 down to 43 grains) and seating 150 Matchkings at 2.766". I was rewarded with a quarter inch group with a muzzle velocity of 2640 fps. With R-P brass, 210M primers, 38 grains of Varget and the 168 Matchkings set at 2.77 ", I got 2454 fps and 3 shot groups just over half an inch. This is understandably a soft recoiling load since 41.5 grains is the max load in the Sierra loading manual. The same powder charge with the 150 grain Matchkings yielded 2480 fps and similar groups. With a compressed charge of 47.5 grains of H4350 in resized FC 308 cases (172 grains in weight) under the 150 grain Matchkings at 2.766", I got 2700 fps and .6 MOA 3 shot groups.
I was using a .185" recoil lug but found that the fired cases were SAAMI minimum minus .001". Consequently, I fitted a .186" lug that put me right at SAAMI minimum, based on the .308 Precision Mic. Checking the bolt lug engagement, I found that one side was carrying most of the load. I lapped the lugs using 220, 320 and 600 grit lapping compound and then made up for the lost metal by installing a thicker .188" recoil lug. This work brought me up to SAAMI minimum plus .001". Checking jam lengths at this point using the F.A. COAL gage resulted in the 140 grain Gamekings measuring 2.791", the 150 Matchkings measuring 2.781", and the 168 Matchkings measuring 2.782". I decided that I needed to try the Hornady 162 Amax bullets but wondered if they were too long to stabilize. The reps at Hornady gave me the length of the bullet as 1.425". Plugging that into the Miller twist rule equation for a 1:9.25 twist barrel and adjusting it for 2600 fps and 20 degrees F, I got a stability factor of s=1.37. That's pretty close to 1.4, so I figured it would work just fine. I bought a box, shot some groups at 25 to 30 degrees and got nice round holes at 100 yards. Varget gave me good groups of .3-.4 MOA at a COAL of 2.954". That's too long for the mag, but they load fine with the single round loading block.
I loaded up some 150 grain Swift Sciroccos over 43.5 grains of H414 and shot some bare 10% ballistic gelatin at 100 yards. The muzzle velocities (not impact velocities) were 2663 and 2664 fps and the bullets penetrated 22.5"and 22", weighed 143 and 141 grains, and expanded to .62" and .61". The 140 grain Accubonds at 2741 and 2745 fps, penetrated 23.5" and 24.5", weighed 110 and 105 grains and expanded to .53" and .54". The 154 grain Interbonds at 2691 and 2664 fps, penetrated 21.5" and 24.5", weighed 144 and 146 grains and expanded to .66" and .69".
The following shots were fired at 30 yards, rather than 100 yards. The 140 grain Trophy Bonded Bearclaw, fired at 2725 fps, went 20" in bare gel, weighed 137 grains and expanded to .65". The Winchester 140 grain Failsafe at 2733 fps weighed 121 grains and expanded to .39". The Speer 145 grain Nitrex Grand Slam at 2621 fps went 24", weighed 116 grains and expanded to .60". These were factory loads.
Tube gun
As I mentioned in the 7-08 section, the feed lip cuts in the action were set up to feed .204s and wouldn't feed the 7-08s. To continue the project I needed to solve this little problem. By switching from the drop floorplate magazine system to the AICS detachable magazine I could use the AICS metal magazines to feed the .308 and all its offspring (.243, .260, 7-08, etc.) and the AICS plastic .223 magazines to feed the .223 and its cousins (.204, .300 Whisper/Blackout, etc). The plastic magazine has the same width and fore/aft measurement as the metal magazine so both types of magazine fit in the same magazine well. My next step was to consider which bottom metal to go with. I had fitted Surgeon bottom metal to a couple of stocks and really like their system. I will use the Surgeon Bottom Metal and a McMillan stock for my youngest son's 700. CDI also makes bottom metal that is affordable but with which I have no experience. Another option, and the one I went with for this rifle, was to glue the action into a Tube Gun Kit. I found an excellent condition MAK XC (across the course) repeater tube gun kit, spare mag and nylon single round loading block for $495 at 6mmBR.com.
MAK (Mike, Archie, Kevin) tube gun kits have been covered in at least two other PS articles written by Robert Whitley (February and October 2004). The benefits of the MAK include ease of set-up as a switch barrel rifle, free floating barrels, no bedding to worry about, weatherproof (aluminum) construction, increased action stiffness and multiple stock options (any AR-15 stock will work). The kit is made up of an aft cap (to which the stock attaches), receiver sleeve (holds the action), sight rail (flat or 20 MOA slope), handguard and trigger guard. Holding it all together are thirteen screws, five of which hold the sight rail. To tighten these screws, especially the action screws, you can use a torque wrench, such as one of the fine Seekonk products. Another option would be to use a Borka adjustable torque wrench. The torque settings change depending on which hex hole you chose - the one shown in the photo allows settings of 36, 43, 50, 57, 65 and 72 inch-lbs. For its features, it's handy, light and priced ri
For a more universal and easy to find caliber choice I have a 24" .223 sporter barrel that was a gift from S. Pence. I made two recoil lug discs/spacers on the lathe. They were .187" and .189" thick, 1.30" OD and 1.065" ID. With the .187" lug the bolt wouldn't close so I fitted the .189" lug in place and it worked just fine. I recrowned the barrel and shot a few firelapping rounds down the barrel to smooth everything out and, yes detractors, increase the jam length about 15 thousandths. On the factory load side, the Black Hills 40 grain Ballistic Tip load left the barrel at 3470 fps, with a group of .5 MOA. With handloads, I had good luck with 24.5 grains of AA2495 in Nosler brass, BR4 primers and 55 grain Berger bullets. With a COAL of 2.317", I got 2960 fps and 3 shot groups averaging .6 MOA. The 52 grain Sierra Matchkings, also pushed by AA2495, are averaging .4 MOA. I feed the .223s using the AI 10 round plastic magazine. It has plenty of room fore and aft inside the magazine to load your cartridges out to an overall length of 2.55" (compared to normal AR-15 magazine length of 2.26").
Extra Bolt (top), wood barrel vise spacers and Surgeon action wrench tool for changing barrels (middle left), Borka adjustable torque wrench(center), nylon single round loading block (middle right), AI 5 round .308 magazine (bottom left), Alpha Industries 10 round .308 magazine (bottom middle) and AI 10 round .223 magazine (bottom right)
7-08
I purchased a used take-off 7-08 barrel for $45. It was blued, 22 inches long and .66" OD at the muzzle. I recrowned it on the lathe and broke the crown's edge with a .45 FMJ bullet smeared with 220 and then 320 grit lapping compound. I threaded it to accept a Ross muzzle brake threaded 5/8-24. The brake is Stainless Steel that I sand blasted with a Campbell Hausfeld sand blaster using play sand strained thru a screen. I wanted the hole to be .030"over bullet diameter so Ross, the brake maker, drilled it out to .314". The brake has 3 chambers with 3 top ports and 3 ports on each side. It cost $40 shipped and was money well spent. I made a spacer .080" thick to time the brake top ports to be top dead center.
I found that 7-08 cartridges won't feed through a 700 that has feed lips intended to feed .204 cartridges. I had read that this would happen but figured I would find out firsthand before I moved to the next step in the project - converting the rifle from a drop floorplate magazine to the detachable AICS magazines. In the mean time, I just single loaded my handloads. I forgot to mention that I have a second bolt to handle the 7-08 and .308 cartridges. Speaking of bolts, you may want to paint barrels and the appropriate bolt that works with them the same color. That is, the 7-08 and .308 barrel could be painted OD green to go with a .462 bolt that is also painted OD. The .204 and .223 barrels could be painted black to go with a .378 bolt that is painted black. If the colors match, you're good to go. That might prevent you from bringing your rifle to the bench with a .223 bolt and a 7-08 barrel. Ask me how I know this.
The jam length for this barrel is around 2.78" for the 7mm Sierra Matchkings in 150 grain and 168 grain weights. That's a pleasant surprise since that COAL is shorter than magazine length. Factory R7M081 ammo loaded with 140 grain PSP bullets averaged 2750 fps and yielded 2 MOA groups. I pulled the bullets and weighed the powder. I loaded some 'Mexican Match' ammo by dropping 2 grains of the powder (from 45 down to 43 grains) and seating 150 Matchkings at 2.766". I was rewarded with a quarter inch group with a muzzle velocity of 2640 fps. With R-P brass, 210M primers, 38 grains of Varget and the 168 Matchkings set at 2.77 ", I got 2454 fps and 3 shot groups just over half an inch. This is understandably a soft recoiling load since 41.5 grains is the max load in the Sierra loading manual. The same powder charge with the 150 grain Matchkings yielded 2480 fps and similar groups. With a compressed charge of 47.5 grains of H4350 in resized FC 308 cases (172 grains in weight) under the 150 grain Matchkings at 2.766", I got 2700 fps and .6 MOA 3 shot groups.
I was using a .185" recoil lug but found that the fired cases were SAAMI minimum minus .001". Consequently, I fitted a .186" lug that put me right at SAAMI minimum, based on the .308 Precision Mic. Checking the bolt lug engagement, I found that one side was carrying most of the load. I lapped the lugs using 220, 320 and 600 grit lapping compound and then made up for the lost metal by installing a thicker .188" recoil lug. This work brought me up to SAAMI minimum plus .001". Checking jam lengths at this point using the F.A. COAL gage resulted in the 140 grain Gamekings measuring 2.791", the 150 Matchkings measuring 2.781", and the 168 Matchkings measuring 2.782". I decided that I needed to try the Hornady 162 Amax bullets but wondered if they were too long to stabilize. The reps at Hornady gave me the length of the bullet as 1.425". Plugging that into the Miller twist rule equation for a 1:9.25 twist barrel and adjusting it for 2600 fps and 20 degrees F, I got a stability factor of s=1.37. That's pretty close to 1.4, so I figured it would work just fine. I bought a box, shot some groups at 25 to 30 degrees and got nice round holes at 100 yards. Varget gave me good groups of .3-.4 MOA at a COAL of 2.954". That's too long for the mag, but they load fine with the single round loading block.
I loaded up some 150 grain Swift Sciroccos over 43.5 grains of H414 and shot some bare 10% ballistic gelatin at 100 yards. The muzzle velocities (not impact velocities) were 2663 and 2664 fps and the bullets penetrated 22.5"and 22", weighed 143 and 141 grains, and expanded to .62" and .61". The 140 grain Accubonds at 2741 and 2745 fps, penetrated 23.5" and 24.5", weighed 110 and 105 grains and expanded to .53" and .54". The 154 grain Interbonds at 2691 and 2664 fps, penetrated 21.5" and 24.5", weighed 144 and 146 grains and expanded to .66" and .69".
The following shots were fired at 30 yards, rather than 100 yards. The 140 grain Trophy Bonded Bearclaw, fired at 2725 fps, went 20" in bare gel, weighed 137 grains and expanded to .65". The Winchester 140 grain Failsafe at 2733 fps weighed 121 grains and expanded to .39". The Speer 145 grain Nitrex Grand Slam at 2621 fps went 24", weighed 116 grains and expanded to .60". These were factory loads.
Tube gun
As I mentioned in the 7-08 section, the feed lip cuts in the action were set up to feed .204s and wouldn't feed the 7-08s. To continue the project I needed to solve this little problem. By switching from the drop floorplate magazine system to the AICS detachable magazine I could use the AICS metal magazines to feed the .308 and all its offspring (.243, .260, 7-08, etc.) and the AICS plastic .223 magazines to feed the .223 and its cousins (.204, .300 Whisper/Blackout, etc). The plastic magazine has the same width and fore/aft measurement as the metal magazine so both types of magazine fit in the same magazine well. My next step was to consider which bottom metal to go with. I had fitted Surgeon bottom metal to a couple of stocks and really like their system. I will use the Surgeon Bottom Metal and a McMillan stock for my youngest son's 700. CDI also makes bottom metal that is affordable but with which I have no experience. Another option, and the one I went with for this rifle, was to glue the action into a Tube Gun Kit. I found an excellent condition MAK XC (across the course) repeater tube gun kit, spare mag and nylon single round loading block for $495 at 6mmBR.com.
MAK (Mike, Archie, Kevin) tube gun kits have been covered in at least two other PS articles written by Robert Whitley (February and October 2004). The benefits of the MAK include ease of set-up as a switch barrel rifle, free floating barrels, no bedding to worry about, weatherproof (aluminum) construction, increased action stiffness and multiple stock options (any AR-15 stock will work). The kit is made up of an aft cap (to which the stock attaches), receiver sleeve (holds the action), sight rail (flat or 20 MOA slope), handguard and trigger guard. Holding it all together are thirteen screws, five of which hold the sight rail. To tighten these screws, especially the action screws, you can use a torque wrench, such as one of the fine Seekonk products. Another option would be to use a Borka adjustable torque wrench. The torque settings change depending on which hex hole you chose - the one shown in the photo allows settings of 36, 43, 50, 57, 65 and 72 inch-lbs. For its features, it's handy, light and priced ri
Tak-MAK, Squak-MAK and Flak-MAK - 3
There a few things to keep in mind about the MAK. First, the stock has to be removed to clean the bore. To do that you must remove two screws that hold the "aft cap" in place and for this you'll need an Alan wrench. I'd prefer to have two knurled big-head screws that could be tightened by hand. I saw some of these at the Jense Precision web site, but since they weren't for sale, I made my own. I used the cut-off .204 barrel muzzle to make two oversized screw heads. I cut two wafers .2" thick and drilled and tapped the wafers ¼-28. I bought some ¼-28 bolts at Lowes, JB Welded them into the screw heads and then cut them to length. Second, an A2 grip attaches behind the trigger guard with one screw, just like any AR, but apparently the contour of the MAK frame above and to the rear of the grip is slightly different. To fit the Magpul MIAD grip with the oversize backstrap, you'll have to MotoTool away a little plastic to get it to fit. That was about a 10 minute job. Third, the MAK is not the lightest setup around, but then again, it wasn't designed to be a sporter. It was designed to be a target rifle. Speaking of target rifles - not all target rifles have safeties. And such is the case with the MAK. It is designed to not have the factory safety installed. I have managed to use an Olympic quality Feinwerkbau 300S air rifle for years without a safety, but on this rifle, I didn't want to disable its working safety.
¼-28 screws plus a cut-off .204 muzzle yield 'big head' stock screws. An original screw is in the center.
Prior to JB Welding the action into the MAK receiver tube, I cut a semicircle in the tube to make room for the safety. I could have purchased a trigger with a bottom safety (like Jewell or Huber) but was out of money, don't like the way they look and have no experience with them. The cutting was uneventful but when I tried to bend the safety lever for a better fit … Snap! … it broke. It must be hardened because it had no give to it at all. That necessitated my making an aluminum safety lever to fit the broken stub. It's glued and screwed in place.
Safety lever is visible inside the cutout, behind the bolt handle
When I purchased the tube gun kit, it had one problem - it was electric blue. I actually liked the color, but since I'm calling this Tak-MAK, as in Taktical, the color had to change. Cutting a notch so the safety can be retained and making a couple big head screws probably doesn't make it Tactical or even Extreme Tactical, but let's not forget that it's black and flat dark earth, sturdy, can chamber several 'tactical' cartridges and has a Harris bipod hanging off it. Just as important - it rhymes. And by naming it I hope to add an air of legitimacy to my gun butchery. Moving on … I degreased all the parts with alcohol and Brownells TCE cleaner and then spray and baked it with GunKote. That was a mistake. I had weighed the options of sandblasting before GunKoting but didn't want to blast off (?) the anodizing. So I hoped that the GunKote would adhere, but it didn't work as well as I'd hoped. The paint chips off at sharp edges, revealing its royal blue pedigree. I sandblasted, degreased, sprayed and baked the bolt with GunKote and it worked fine, so there's nothing wrong with the product, but apparently you shouldn't use it over anodized aluminum without sandblasting it first. Oh well, a little flat black Rustoleum spray paint touches it right up.
My handguard accepts a handstop by way of an accessory slot at 6 o'clock. You can also order the handguard without the accessory slot. There is one threaded hole for a QD sling stud just ahead of the slot, but it sits far enough forward that the Harris bipod base overhangs the front edge of the handguard. Not caring for that arrangement, I made a threaded T slot nut that fits in the accessory slot, accepts the QD sling stud and provides an attachment point for the Harris bipod. For night time adventures, I drilled and tapped two 10-24 holes at 10 o'clock so that I could attach a short section of Picatinny rail. The rail gives a Streamlight a place to sit.
I used a fixed A1 stock for this project, but the longer A2 stock, a Magpul PRS or one of the many collapsible stocks would also make good choices. I cut off the sling swivel flush with the bottom of the stock so that it would ride the sandbags better. With the stock removed, the overall length of the rifle is about 11 inches longer than the barrel length. So if a collapsed 14.5 inch M4 (31" long) will fit in your gun case, then the MAK with a 20 inch barrel and the stock removed will fit it to. Just put the stock in one of the accessory pouches.
Here are some weights related to this project: A1 stock with Aft cap - 1.33 lbs. Handguard with QD stud - .65 lbs. 7-08 22" skinny barrel with spacer - 2.45 lbs. .223 24" skinny barrel with recoil lug - 2.88 lbs. .204 heavy barrel with spacer - 4.33 lbs. .308 18" heavy barrel - 3.27 lbs. AI 5 round mag loaded with .308s - .62 lbs. Receiver sleeve with Rem 700 receiver, bolt, trigger, safety, trigger guard with pistol grip, scope rail - 4.06 lbs. .204 barrel with handguard, stock, action - 10.37 lbs ditto plus Harris bipod and 3.5-10x scope - 12.4 lbs. 7-08 complete rifle with 6.5-20X scope, bipod, 5 round AI mag - 11.30 lbs.
308
The .308 barrel started life as a factory Remington Varmint profile 24" barrel. I cut the barrel with a hacksaw to a handier 18" and asked Eric to give it a USMC PWS crown. The muzzle diameter was .86". I threaded the barrel into the action with a go-gage held in the bolt face and the barrel stopped with a .183" gap between the front face of the action and the barrel shoulder. I had a recoil lug .186" thick that I figured would provide a headspace measurement between min and max. I cut and filed the bottom of the lug off to make a recoil spacer that would allow the handguard to fit in place over the receiver sleeve. It looked sort of cheesy (not that anyone could see it) so I put the lug on the lathe and cleaned up the outside bottom surface. I got the following velocities from factory ammo with this 18 inch barrel: 130 Norma - 2780 fps, Federal 150 Ballistic Tip - 2700 fps, 155 Scenar - 2655 fps, Remington 165 Ballistic Tip - 2590 fps, 168 TAP AMax - 2530 fps, 175 Federal Gold Medal - 2455 fps and Black Hills 175 Match - 2470 fps. Five shot groups of 168 TAP Amax and 175 Gold Medal run around .8 to .9 MOA. The Black Hills 175 Match runs around .75 MOA for 3 shot groups.
I cut off a second take-off Varmint barrel from Mr. Del at 20"and crowned it using the Manson muzzle crown refacing kit available from Brownells. Firing TAP 168 AMax, I got a 5 shot group measuring .99" but that included the Cold Bore Shot (CBS). Shots 2 thru 5 measured .49". The second five shot group measured .50". Lapua Scenar 155 grainers shot into .65". Some rounds loaded with 168 grain Berger bullets shot less than .5 MOA. The Sellier & Bellot 168 HPBT Match ammo shot about 1.25 MOA and some Hornady Superformance 178s shot around 1.5 MOA.
To switch barrels, I use the Surgeon action wrench and a barrel vise. The Surgeon action wrench fits into the ejection port rather than fitting in the back end of the action. The advantage of this is that you don't need to remove the stock to change barrels. Also I save a little more time by not removing the handguard while changing barrels. I just clamp the barrel ahead of the handguard, using the appropriate wood inserts in the barrel vise. I made several wood inserts that have varying inside diameters to fit the different barrels I have. I don't twist the barrels on too hard since I like to change them without pulling a muscle. A couple things I'm still experimenting with regarding accuracy are the torque setting used to tighten the barrel along with using Teflon tape to limit the slop between the barrel and action threads. I want the barrel screwed on tight enough to give me the barrels best accuracy, but not so tight that it's difficult to change.
I have had good luck with two types of magazine for the .308 and 7-08 ammo. The first is the 5 round magazine made by AI (that comes with the MAK kit). The second is an Alpha Industries Type 1 10 round magazine. It's only a little longer than the AI 5 round mag and is shorter than the AI 10 round mag. It's made from stainless steel with a black Teflon finish and is made in the USA. It accepts ammo up to 2.85" long. The Type 2 magazine doesn't have a spacer welded in the front of the magazine so it accepts ammo up to 2.98" long but needs to have the feed ramp modified to work properly. There is also a third magazine made by C-Products that is an AICS compatible magazine, but I have no first-hand e
MAK Enterprises, 1017 Wildwood Ct., Seymour, IN 47274, 812-523-6769 or 812-522-8837, www.tubegun.net
Alpha Industries magazines, PO Box 5127, Fullerton, CA 92838-5127, www.alphaindmfg.com
Ross side discharge muzzle brakes - Ross Schuler, 261 Victor Gust Drive, Mountain Home, Idaho 83647, [email protected]
Borka Adjustable Torque Driver, model ATD-36x72-06FS, www.brownells.com
Surgeon Action Wrench, www.surgeonrifles.com
xperience with it. For clarification, whenever I use 'AI' in this article, it stands for Accuracy International and should not be confused with Alpha Industries, which could also be shortened to AI.
The last MAK variant, for which I have no photo, is the rare and elusive Flak-MAK. You may be interested in knowing that Flak is an acronym taken from Flieger Abwehr Kanone (anti-aircraft gun.) The purpose of the Flak-MAK is to engage low flying, slow moving, uninvited aerial intruders, utilizing extended four column magazines, triplex tracer depleted uranium sabot ammo and a Pederson-like device, thus converting the rifle to full auto fire. In addition to burning out a barrel in short order, the tripod is heavy and the anti-aircraft sights cumbersome. Since this is only a concept at this point, I guess my boys and I will have to spend all our time blasting away with the more popular and practical Squak-MAK and Tak-MAK.
¼-28 screws plus a cut-off .204 muzzle yield 'big head' stock screws. An original screw is in the center.
Prior to JB Welding the action into the MAK receiver tube, I cut a semicircle in the tube to make room for the safety. I could have purchased a trigger with a bottom safety (like Jewell or Huber) but was out of money, don't like the way they look and have no experience with them. The cutting was uneventful but when I tried to bend the safety lever for a better fit … Snap! … it broke. It must be hardened because it had no give to it at all. That necessitated my making an aluminum safety lever to fit the broken stub. It's glued and screwed in place.
Safety lever is visible inside the cutout, behind the bolt handle
When I purchased the tube gun kit, it had one problem - it was electric blue. I actually liked the color, but since I'm calling this Tak-MAK, as in Taktical, the color had to change. Cutting a notch so the safety can be retained and making a couple big head screws probably doesn't make it Tactical or even Extreme Tactical, but let's not forget that it's black and flat dark earth, sturdy, can chamber several 'tactical' cartridges and has a Harris bipod hanging off it. Just as important - it rhymes. And by naming it I hope to add an air of legitimacy to my gun butchery. Moving on … I degreased all the parts with alcohol and Brownells TCE cleaner and then spray and baked it with GunKote. That was a mistake. I had weighed the options of sandblasting before GunKoting but didn't want to blast off (?) the anodizing. So I hoped that the GunKote would adhere, but it didn't work as well as I'd hoped. The paint chips off at sharp edges, revealing its royal blue pedigree. I sandblasted, degreased, sprayed and baked the bolt with GunKote and it worked fine, so there's nothing wrong with the product, but apparently you shouldn't use it over anodized aluminum without sandblasting it first. Oh well, a little flat black Rustoleum spray paint touches it right up.
My handguard accepts a handstop by way of an accessory slot at 6 o'clock. You can also order the handguard without the accessory slot. There is one threaded hole for a QD sling stud just ahead of the slot, but it sits far enough forward that the Harris bipod base overhangs the front edge of the handguard. Not caring for that arrangement, I made a threaded T slot nut that fits in the accessory slot, accepts the QD sling stud and provides an attachment point for the Harris bipod. For night time adventures, I drilled and tapped two 10-24 holes at 10 o'clock so that I could attach a short section of Picatinny rail. The rail gives a Streamlight a place to sit.
I used a fixed A1 stock for this project, but the longer A2 stock, a Magpul PRS or one of the many collapsible stocks would also make good choices. I cut off the sling swivel flush with the bottom of the stock so that it would ride the sandbags better. With the stock removed, the overall length of the rifle is about 11 inches longer than the barrel length. So if a collapsed 14.5 inch M4 (31" long) will fit in your gun case, then the MAK with a 20 inch barrel and the stock removed will fit it to. Just put the stock in one of the accessory pouches.
Here are some weights related to this project: A1 stock with Aft cap - 1.33 lbs. Handguard with QD stud - .65 lbs. 7-08 22" skinny barrel with spacer - 2.45 lbs. .223 24" skinny barrel with recoil lug - 2.88 lbs. .204 heavy barrel with spacer - 4.33 lbs. .308 18" heavy barrel - 3.27 lbs. AI 5 round mag loaded with .308s - .62 lbs. Receiver sleeve with Rem 700 receiver, bolt, trigger, safety, trigger guard with pistol grip, scope rail - 4.06 lbs. .204 barrel with handguard, stock, action - 10.37 lbs ditto plus Harris bipod and 3.5-10x scope - 12.4 lbs. 7-08 complete rifle with 6.5-20X scope, bipod, 5 round AI mag - 11.30 lbs.
308
The .308 barrel started life as a factory Remington Varmint profile 24" barrel. I cut the barrel with a hacksaw to a handier 18" and asked Eric to give it a USMC PWS crown. The muzzle diameter was .86". I threaded the barrel into the action with a go-gage held in the bolt face and the barrel stopped with a .183" gap between the front face of the action and the barrel shoulder. I had a recoil lug .186" thick that I figured would provide a headspace measurement between min and max. I cut and filed the bottom of the lug off to make a recoil spacer that would allow the handguard to fit in place over the receiver sleeve. It looked sort of cheesy (not that anyone could see it) so I put the lug on the lathe and cleaned up the outside bottom surface. I got the following velocities from factory ammo with this 18 inch barrel: 130 Norma - 2780 fps, Federal 150 Ballistic Tip - 2700 fps, 155 Scenar - 2655 fps, Remington 165 Ballistic Tip - 2590 fps, 168 TAP AMax - 2530 fps, 175 Federal Gold Medal - 2455 fps and Black Hills 175 Match - 2470 fps. Five shot groups of 168 TAP Amax and 175 Gold Medal run around .8 to .9 MOA. The Black Hills 175 Match runs around .75 MOA for 3 shot groups.
I cut off a second take-off Varmint barrel from Mr. Del at 20"and crowned it using the Manson muzzle crown refacing kit available from Brownells. Firing TAP 168 AMax, I got a 5 shot group measuring .99" but that included the Cold Bore Shot (CBS). Shots 2 thru 5 measured .49". The second five shot group measured .50". Lapua Scenar 155 grainers shot into .65". Some rounds loaded with 168 grain Berger bullets shot less than .5 MOA. The Sellier & Bellot 168 HPBT Match ammo shot about 1.25 MOA and some Hornady Superformance 178s shot around 1.5 MOA.
To switch barrels, I use the Surgeon action wrench and a barrel vise. The Surgeon action wrench fits into the ejection port rather than fitting in the back end of the action. The advantage of this is that you don't need to remove the stock to change barrels. Also I save a little more time by not removing the handguard while changing barrels. I just clamp the barrel ahead of the handguard, using the appropriate wood inserts in the barrel vise. I made several wood inserts that have varying inside diameters to fit the different barrels I have. I don't twist the barrels on too hard since I like to change them without pulling a muscle. A couple things I'm still experimenting with regarding accuracy are the torque setting used to tighten the barrel along with using Teflon tape to limit the slop between the barrel and action threads. I want the barrel screwed on tight enough to give me the barrels best accuracy, but not so tight that it's difficult to change.
I have had good luck with two types of magazine for the .308 and 7-08 ammo. The first is the 5 round magazine made by AI (that comes with the MAK kit). The second is an Alpha Industries Type 1 10 round magazine. It's only a little longer than the AI 5 round mag and is shorter than the AI 10 round mag. It's made from stainless steel with a black Teflon finish and is made in the USA. It accepts ammo up to 2.85" long. The Type 2 magazine doesn't have a spacer welded in the front of the magazine so it accepts ammo up to 2.98" long but needs to have the feed ramp modified to work properly. There is also a third magazine made by C-Products that is an AICS compatible magazine, but I have no first-hand e
MAK Enterprises, 1017 Wildwood Ct., Seymour, IN 47274, 812-523-6769 or 812-522-8837, www.tubegun.net
Alpha Industries magazines, PO Box 5127, Fullerton, CA 92838-5127, www.alphaindmfg.com
Ross side discharge muzzle brakes - Ross Schuler, 261 Victor Gust Drive, Mountain Home, Idaho 83647, [email protected]
Borka Adjustable Torque Driver, model ATD-36x72-06FS, www.brownells.com
Surgeon Action Wrench, www.surgeonrifles.com
xperience with it. For clarification, whenever I use 'AI' in this article, it stands for Accuracy International and should not be confused with Alpha Industries, which could also be shortened to AI.
The last MAK variant, for which I have no photo, is the rare and elusive Flak-MAK. You may be interested in knowing that Flak is an acronym taken from Flieger Abwehr Kanone (anti-aircraft gun.) The purpose of the Flak-MAK is to engage low flying, slow moving, uninvited aerial intruders, utilizing extended four column magazines, triplex tracer depleted uranium sabot ammo and a Pederson-like device, thus converting the rifle to full auto fire. In addition to burning out a barrel in short order, the tripod is heavy and the anti-aircraft sights cumbersome. Since this is only a concept at this point, I guess my boys and I will have to spend all our time blasting away with the more popular and practical Squak-MAK and Tak-MAK.
