The Texas 260 (Shooting Steel At A Mile)
By Alan Marshall
©Copyright Precision Shooting Magazine
"This is crazy," I repeated out loud as the Kestrel indicated winds over 35 mph. The Texas winds were blowin' and we were shootin'. "This is insane," I said again as I held 4 mils into the wind. I shouldn't have been surprised though – I had seen the huge wind turbines spinning in the wind as we flew into Amarillo. Add this location to others that should have high-wind "Small Dog Warnings."
The 260 Tak-MAK is in the foreground and a Surgeon 338 Lapua Magnum is in back. This was our location for shooting the mile target.
This project began as I prepared for some long range shooting at Accuracy First, located in Canadian, Texas. Most of the class members were repeat customers while I would be one of the newbies. While the majority of the class planned on using a 308 with the 175 grain Sierra MatchKing (SMK), I hoped to use a round with a higher BC and muzzle velocity – you know, if you can't beat them with skill, try to beat them with technology. For mile shooting, it's been suggested that you choose a bullet that transitions well into subsonic flight, even if that means you're not choosing a bullet that has the highest BC. Of course the ideal solution is a bullet that has both a high BC and transitions well. I read of shooters having success at a mile using the high BC 6.5mm 140 grain A-MAX and 142 grain SMK bullets. I contacted Robert Silvers at AAC and asked him what kind of accuracy I could expect from the fast twist AAC 260 Remington barrels. He responded with an offer to let me try five of the barrels and then choose the one I wanted, if any. Sounded like a plan to me, since I already had about 1200 mid to heavy weight 6.5mm bullets on hand (for my 6.5 RathuvAL).
Gun Details
The rifle I took was a right hand Remington 700 short action. I'm left-handed, but I don't find that shooting a right-handed gun is a handicap when shooting prone or off the bench. This action is glued into a MAK tube gun, which has proven to shoot pretty well. The trigger is factory and breaks at 3.25 pounds. The stock is homegrown and has a vertically adjustable recoil pad and toe. The grip is a Magpul MIAD that I shortened so that it wouldn't dig into the ground with the adjustable toe set at its "up" position. The AAC 260 barrels are 24 inches long, have a 1:8 twist and a black "Scarmor" QPQ Nitride finish. The salt bath nitride surface conversion makes the inside and outside surfaces of the 4140 steel very corrosion resistant and very hard. It is also supposed to last about 60% longer than chrome lined barrels. The barrel weighs 4.74 pounds (a bit heavier than the 4.06 pounds for a 308 PSS 24? barrel). Headspacing is accomplished by using a recoil lug of the appropriate thickness. I installed the barrel(s) by smearing a little anti-seize lube on the threads, and then I hand-tightened the barrel with a 308 go-gauge in the chamber but no recoil lug (what Remington calls a barrel bracket) in place. Once the barrel stopped against the go-gauge I measured the gap between the action face and the barrel shoulder. I then installed a recoil lug of the appropriate thickness and ended up with a .000? reading (SAAMI minimum reading) using a 308 Precision Mic. The recoil lug I used on barrel #1 is .189? thick. The second and fourth barrel also used the same thickness recoil lug. Strictly speaking the MAK uses a recoil disc, rather than lug, but I used the term "lug" since it is more familiar.
The muzzle is threaded 5/8-24 for a suppressor or muzzle brake, and I elected to use a stainless steel muzzle brake made by Ross Shuler. Its diameter is one inch, it cost $35 and was money well spent. I needed a few shims to time it with the top ports at 12 o'clock. After beveling the back of the brake, I sandblasted and then painted it. Moving back to the handguard, I drilled and tapped it to accept a Picatinny rail that I located at 12 o'clock. Onto this rail I mounted a US Optics level, which allows me to see and adjust the level before I pull the trigger. Some scope levels are scope mounted, but with my aging eyes, it works better to have the level further away, out at the end of the handguard. The scope I used was the Bushnell 3.5-21X with a Horus H58 reticle and .1 mil windage and elevation adjustments. The scope worked well except at one mile, where I couldn't dial out all the parallax. I had Todd take a look and he couldn't dial it out either. (Editor: Do it the easy way. Skip any one mile matches until the summer is over...)
My stock work is shown in the photo at right. The top knurled screw secures the vertically adjustable recoil pad in place. The bottom knurled screw secures the vertically adjustable toe in place. The paracord is the rear sling attachment point for HK style slings. The adjustable toe fits into the sandbag ears and can be adjusted up and down about an inch. What I like about a standard stock with the angled toe running up to the pistol grip is that you can make elevation changes by running the sandbag fore and aft. The down side is that during recoil, the muzzle rises as the stock moves back and down. With a flat bottom stock (that is, the toe of the stock running parallel with the barrel) the muzzle doesn't tend to rise as the stock moves to the rear, but it is necessary to change the bipod height or front rest height to make elevation changes. With an adjustable toe, you get the straight back recoil and it's easier to make elevation adjustments since you don't have to reach forward to adjust the height of the bipod.
I broke in the barrel, sort of, using a shoot one and clean regimen for the first five shots. Then I moved forward with "the Quest" – looking for the accurate load(s). With 142 Sierra MatchKing (SMK) moly coated bullets over 47 grains of H4831SC, I shot a three shot group of .41?. That looked promising so I loaded up five more rounds and shot a five shot group of .68? at 100 yards. Velocities ran from 2730 to 2757 fps with this load that is one grain under the max listed in the Hodgdon manual. I tried the same load with the second barrel and got slightly higher velocities.
Barrel #1 accuracy results: I fired about 50 rounds through this barrel and averaged .80 MOA three shot groups for all the groups, good and bad, at 100 yards. If I fired it, it's included in the average. No rounds were thrown out. The smallest groups were fired with the 142 Sierra MatchKing (SMK) bullets loaded .008? off the lands. The last group, a five rounder, measured .68? and clocked 2742 fps. That looked OK, but I still had time before leaving for Texas so I unthreaded Barrel #1 and threaded on Barrel #2.
Barrel #2 accuracy results: Prior to leaving for Texas, I fired about 110 rounds through this barrel, with an average three shot group size of .71 MOA. My best two groups were with the 123 grain Scenars (.21?) and the 140 A-MAX (.24?). Since this barrel shot marginally better than barrel #1 and it was time for the course to begin, I decided to take this barrel to Texas. I shot about 210 of the moly 140 A-MAXes at Canadian and have no complaints. Since I didn't clean the barrel at all while I was there, I shot a group at 100 yards when I returned to my home range, to see how the lack of cleaning affected the accuracy. That five shot group measured .72?. I consider that group size (≈3/4 MOA) to be typical for the run of the mill military and LE sniper rifle. I've seen better than that, but not very often.
Dies
While I was waiting for the barrels to arrive I got started on the brass and dies. The dies I started with were RCBS and Hornady New Dimension. I set up the full length sizers to push the shoulder back to SAAMI minimum minus .002?. By the way, don't change shellholders after you set up the dies or you might change the headspace. For my two shellholders, the difference is .002? and one shellholder makes firm contact with the bottom of the die, while the other does not. The Hornady dies reduce the shoulder diameter from .457? (fired) to .452?, and size the ID of the case mouth to .260?. The RCBS dies reduce the shoulder diameter to .454? and the neck to .260?. After working on barrels 1 and 2, I purchased the Lee Collet die set so that I could size just the neck. It initially sized the neck ID to .262?, but I polished the decap mandrel down to .260? to give the neck a tighter bite on the bullet and match the other dies. I like the Collet dies, and it's nice not having to mess with lube before and after sizing cases.
The Wind Course. Notice that the lanyards hanging at the bottom of the Kestrels are whipping in the wind. Cell phone photo courtesy of Todd.
The concentricity of my loaded ammo is typically .002? or .003?. The worst I've measured was .005?. I'm not saying that's great, I'm just sayin' that's what it is. By comparison, Federal's 308 Gold Metal Match averages .004? whenever I've checked it. I don't think I'll get the concentricity any lower without turning the necks.
Ammo
The brass (300 pieces) arrived in six 51-piece bags and was made by Remington. I started sorting them by weight, in .5 grain increments. What I ended up with was the following, shown in Table 1.
I checked them for length and trimmed those that were over 2.031?. Most fell in the 2.029? to 2.031? range. Then I chamfered the case mouths and deburred the flash hole. Finally I full length sized them all and primed them with Winchester WLR primers. I was going to buy GM210 primers but Sinclair was out and the nice guy that answered the phone said that he used the WLRs in his long range rifle. When I handload the ammo I keep the brass segregated in its half-grain groups.
I checked the jam lengths for the following bullets in barrels 1 to 5.
I do have two types of 140 grain A-MAX bullets, some older ones and the new AMP versions. The jam lengths and overall lengths differ between the old and the new. For example, barrel #3 has a jam length of 2.836? for the old 140 A-MAX and 2.866? for the new 140 A-MAX. The old A-MAX is 1.367? long and the new AMP A-MAX is 1.379? long.
Each barrel was checked for accuracy using six to eight different types of the above listed bullets. The Alpha Industries 10 round magazine that I use can handle cartridge lengths up to 2.89? so I can load all these rounds as far out as I need and still cycle them through the magazine.
I happened to meet Troy Lawton (AMU) at an ammo meeting. I asked him if he had any recommendations for 260 loads. He recommended H4350 and mentioned firing the 142 SMKs at 600 and the 107s or 123s at 200 and 300. I did use H4350 for my loads that I took to Texas. H4350 is part of the Hodgdon Extreme line of powders, known for their temperature insensitivity.
Canadian Adventures
We arrived at Accuracy First on a Monday morning, with the prospect of three windy days in the 70s, followed by a rainy or snowy day. As such, we decided to spend as much time outside the first three days and then have more classroom time on Thursday. Mr. Beaufort and I decided to mix our shooting between the school guns (LaRue 18? 308 OBR rifles with Horus Tremor reticles) and our own rifles (my 260 and his 338 Lapua Magnum) with Horus H58 reticles. With that plan in mind we headed to the 100 meter range and zeroed our rifles. This was my first exposure to shooting in real wind – not the gentle breezes of Virginia but the full blown winds of Texas. The wind blows dirt and sand into everything. That's eyes, ears, bolt, safety, magazine, pockets, ammo boxes – well, you get the idea. My safety became non-functional at this point due to blowing sand. The bolt release also became barely functional. We left the 100 meter range and headed out to one of the ranges to "true" our guns. The concept here is to shoot the gun at a distance where the bullet goes transonic (around 850 meters with the 308) and see what its drop is. You tell the computer what the drop is at that distance and it will adjust the velocity or BC to match what you just found. I trued the rifle at 1045 meters, where my come-up from the 100 meter zero was 9.5 mils. My bullet wasn't transonic there but it was far enough out to be useful. Using the environmentals of the time I told my Kestrel that my muzzle velocity was 2775, that my bore height was 2.91?, that the barometric pressure was 27 (IIRC), etc. and that it took 9.5 mils to hit at 1045 meters. It figured out that I would need a G1 BC of .64 for that to be true. Based on that, the Kestrel made a range card in 10 yard increments. Using a Vectronix Terrapin L5, we lased our targets or mil'ed them to determine their range and then the Kestrel told us our mil holds. At 790 meters I held 6.2 mils and hit one out of five shots. My hold at 475 was 2.5 mils, at 520 it was 3 mils, at 700 it was 4.8 mils and at 890 meters my hold-over was 7.3 mils.
Monday afternoon we grabbed the OBRs and headed to the Golf Course. Todd would tell us what "par" was for each station and then we would mil the target, determine our range and make a wind call. If the target was more than 600 meters away, Todd would tell us the distance. If the range was less than 600 meters, we had to mil the targets to determine their distance. The targets were either 12 inch steel circles or 12 inch circles on top of 16 inch steel squares. The OBR I was using had the Tremor reticle. Hash marks in .1 mil increments were used to determine how far away the target was. For example, a 12 inch plate that appeared .6 mils high (or wide) was 508 meters away. Once we had the range, we used the Kestrel to determine wind speed. Then we determined if the wind was full value, no value or somewhere in between. Based on that, we made a wind call. Todd had formulas for this, and the reticle had wind dots that helped us with our holds. At one location, Todd pointed out how the wind became audible at 16 to 18 mph. I hadn't noticed that – of course, I had my hard ears on. One, to protect my ears from a 338 with a muzzle brake, and two, to keep the wind from blowing off my cover. The first plate was a par 2 and I hit it on the second shot. The second plate was at 705 meters and was a par 3. I hit it on the third shot at 6 mils elevation and holding 7 wind dots into the wind. I think most of the stations were par 1 to par 3 and as I look at my notes I see some 4s and 5s. On a positive note, as I got to the end of the course, I hit the 743 meter target (a par 3) on the second shot. The last shooting location was at the top of a steep hill. We were encouraged to hear that the Marine Snipers ran from station to station. Twenty-five years ago I would have tried that, minus gun and gear, but those days are long past. So with all the speed of a glacier, I eased my way to the top of the hill and got one shot off – a hit – before the sun dropped below the horizon and my reticle disappeared into the darkness. That ended day one.
We headed to the Cattle Exchange restaurant, ate a trough full and then finished it off with bread pudding. For what it's worth – it's really not pudding – it's more like cobbler. I made a mental note that it took two Cokes to wash all the grit out of my teeth. Mr. Beaufort said, "I think I got a rock stuck in my moustache." I have no doubt.
On Tuesday we grabbed the OBRs in the morning and then traded them out for our personal guns for the afternoon Wind Course. (See photo 3). It's called the Wind Course for obvious reasons, and your score doesn't count unless the winds are at least 15 mph sustained. Our scores counted since we had a max wind reading of 37 mph. Your score is determined by getting 2 points for a first round hit on a target and 1 point for a second round hit. There are 15 targets (we only saw 13) located around the top 360 degrees of the hill. Max score is 30. The course record was set by Scott last year and stands at 17. I tied Mr. Beaufort with a whopping 6. I got a point on the 318 meter target, one at 467, one at 632, two at 530 and one at 450. The targets placed at 650 to 800 meters were completely safe. Scared maybe – from close misses – but safe. I wore some very fashionable goggles that kept my eyes from tearing up and getting sandblasted. I carried my gear in an Eberlestock Gunslinger pack (GS05ME) that has a rifle pocket big enough to carry the OBR or my Tak-MAK. It also carried my water, trail mix, rangefinder, Kestrel, notebook, sandbag, goggles and first aid kit. There's room for more than that but I was trying not to weigh myself down with a hundred pounds of lightweight gear. We left our shooting mats (5 lbs) behind for the same reason, not to mention that the steely eyed death merchants we were with didn't carry pads so we didn't want our lacy undies to show. Fortunately, the occasional hit waaay out there took our minds off the rocks we were laying on.
Wednesday was the day we went for The Mile Shot. We started out at some closer range targets before working up to 1609 meters (one mile). We shot at 340, 660, 688, 760 and 794 meters. Then at 1000 meters I held 9 mils and held 3.4 mils into the wind. At 1070 meters we found a 12 inch plate painted black. I hit it with a hold of 10 mils and 2.7 mils into the wind. At 1270 meters I held 14 mils elevation and 4 mils into the wind. Finally it was time to shoot into a different time zone/zip code. I lazed the target twice and got 1610 and 1611 meters. Mr. Beaufort went first, with his 338, shooting 250 grain BTHPs. His elevation ended up being 18.5 mils. By contrast, we asked the OBR shooters what they were holding and they were at 34 mils. After he whacked the steel (12 inch circle over a 16 inch square) a few times, it was my turn with the 260. I came up 13 mils on the elevation dial (I only had 14 mils left on the dial) and then held 8 more mils on the reticle. No joy – no puff of dirt could be seen. Hold 9 mils and let fly. No joy. Hold 10 mils and let fly. Yeah – a puff of dirt marked the impact. From there I was able to adjust for the wind and start hitting on and around the steel. In total, I hit the steel three times with the 260 (witnessed). I connected with holds from 23 to 24 mils and 2 to 4 mils into the wind. The parallax at the bottom of the field of view in the scope was running from the top to the bottom of the target. That plus the changeable wind, plus my belly shooting (dis)abilities, plus the elevation variations due to muzzle velocity variations (about 23? worth of vertical between 2771 and 2789 fps) and I'm amazed that I ever hit anything at that distance. After hitting the target with the 260 I gave the 338 a try. On the tenth shot I rang the steel with one of the 250 grainers. I got back to the hotel and wrote in my notebook, "Good day in Canadian. The wind was 16 mph, which sure beats 37. No grit in my teeth today. I hit the mile target three times with the 260 and once with the 338. I had beef quesadillas and bread pudding for supper and a lady (Dianne) left cookies for us at the hotel." Pretty friendly locals. Thanks, Dianne.
The ballistic solver that I used was the Kestrel 4500 NV Horus. It combines wind speed, pressure, temperature, etc. with a PDA. You can call up a range card that calculates holds for elevation and windage in 10 yard or greater increments. It's a really sturdy unit that put up with all the blowing dirt and kept ticking. The battery life is also very good. With the "environment" turned on, the unit constantly updates the meteorological data and changes the range card to account for the changes. You can enter and save a bunch of guns in memory and then pick the one you're using. I entered 260 Rem, 2775 fps, .60 BC (G1), 140 grain, .264 diameter, 100 meter zero, 2.91? sight height and right hand 1:8 twist barrel. You may have noticed that I said the effective BC was .64 earlier in the article, which is true, but I had to lower it to .60 to agree with the come ups out to a mile. Apparently the transition to subsonic flight made the difference. Or something(?). Hey, if I had all the answers, I'd write a book.
Barrel #3 accuracy results: Getting back to work after I returned from Texas, I installed barrel #3 and shot about one hundred rounds through it – averaging .80 MOA for its three shot groups. The 130 Norma shot a .55? three shot group at .020? off the lands. A follow on five shot group measured .65?. The meplat on that bullet sure is small. The best group with this barrel, a .24?, was with the 142 SMK over 38 grains of Varget, at 2638 fps.
Barrel #4 accuracy results: I fired 120 rounds with an average three shot group size of .81 MOA for all the groups. My best groups include the 140 Berger VLD at .37?, the 140 A-MAX at .35?, the 142 SMK at .29? and the 123 Scenar at .20?.
Barrel #5 accuracy results: Up until this barrel I felt that the performance of the barrels was pretty similar, running .7 to .8 MOA, and I wasn't expecting #5 to be much different. Then I started shooting this barrel. The second outing I put up a sheet of paper with eight orange dots to record my eight three shot groups. I loaded 39.5 grains of Viht N150 under various seating depths of 139 grain Scenars, 140 grain A-MAX bullets and 142 grain SMKs. I averaged .44? for the eight groups. The best group was .20? with the A-MAX bullets. These were the old style, pre AMP bullets. For the next day's outing I loaded five rounds of this same load plus some other new loads. Scott hadn't shot a 260 so he volunteered to do the shooting. I showed him the .20? group and told him that all I needed was nothing less than his absolute best shooting. I was watching through the big Unertl spotting scope as he punched out a .34? five shot group. Yep, that'll work. I think I'll hold onto this barrel.
The 140 grain A-MAX is a target bullet, but that didn't stop me from thumping a block of 10% ballistic gelatin with it at an impact velocity of 2751 fps. The bullet penetrated 13 inches, expanded to .66? and weighed 63 grains. The bullet expansion started immediately – no neck length. I also shot a few other bullets into the ballistic gelatin with the photo and penetration results shown below.
Contacts:
Accuracy 1st, Inc.
[email protected]
Eberlestock packs
www.Eberlestock.com
877-866-3047
Horus reticles and Kestrel ballistic solvers
www.horusvision.com
650-588-8862
Vectronix
Laser range finders
www.vectronix.ch
703-777-3900
By Alan Marshall
©Copyright Precision Shooting Magazine
"This is crazy," I repeated out loud as the Kestrel indicated winds over 35 mph. The Texas winds were blowin' and we were shootin'. "This is insane," I said again as I held 4 mils into the wind. I shouldn't have been surprised though – I had seen the huge wind turbines spinning in the wind as we flew into Amarillo. Add this location to others that should have high-wind "Small Dog Warnings."
The 260 Tak-MAK is in the foreground and a Surgeon 338 Lapua Magnum is in back. This was our location for shooting the mile target.
This project began as I prepared for some long range shooting at Accuracy First, located in Canadian, Texas. Most of the class members were repeat customers while I would be one of the newbies. While the majority of the class planned on using a 308 with the 175 grain Sierra MatchKing (SMK), I hoped to use a round with a higher BC and muzzle velocity – you know, if you can't beat them with skill, try to beat them with technology. For mile shooting, it's been suggested that you choose a bullet that transitions well into subsonic flight, even if that means you're not choosing a bullet that has the highest BC. Of course the ideal solution is a bullet that has both a high BC and transitions well. I read of shooters having success at a mile using the high BC 6.5mm 140 grain A-MAX and 142 grain SMK bullets. I contacted Robert Silvers at AAC and asked him what kind of accuracy I could expect from the fast twist AAC 260 Remington barrels. He responded with an offer to let me try five of the barrels and then choose the one I wanted, if any. Sounded like a plan to me, since I already had about 1200 mid to heavy weight 6.5mm bullets on hand (for my 6.5 RathuvAL).
Gun Details
The rifle I took was a right hand Remington 700 short action. I'm left-handed, but I don't find that shooting a right-handed gun is a handicap when shooting prone or off the bench. This action is glued into a MAK tube gun, which has proven to shoot pretty well. The trigger is factory and breaks at 3.25 pounds. The stock is homegrown and has a vertically adjustable recoil pad and toe. The grip is a Magpul MIAD that I shortened so that it wouldn't dig into the ground with the adjustable toe set at its "up" position. The AAC 260 barrels are 24 inches long, have a 1:8 twist and a black "Scarmor" QPQ Nitride finish. The salt bath nitride surface conversion makes the inside and outside surfaces of the 4140 steel very corrosion resistant and very hard. It is also supposed to last about 60% longer than chrome lined barrels. The barrel weighs 4.74 pounds (a bit heavier than the 4.06 pounds for a 308 PSS 24? barrel). Headspacing is accomplished by using a recoil lug of the appropriate thickness. I installed the barrel(s) by smearing a little anti-seize lube on the threads, and then I hand-tightened the barrel with a 308 go-gauge in the chamber but no recoil lug (what Remington calls a barrel bracket) in place. Once the barrel stopped against the go-gauge I measured the gap between the action face and the barrel shoulder. I then installed a recoil lug of the appropriate thickness and ended up with a .000? reading (SAAMI minimum reading) using a 308 Precision Mic. The recoil lug I used on barrel #1 is .189? thick. The second and fourth barrel also used the same thickness recoil lug. Strictly speaking the MAK uses a recoil disc, rather than lug, but I used the term "lug" since it is more familiar.
The muzzle is threaded 5/8-24 for a suppressor or muzzle brake, and I elected to use a stainless steel muzzle brake made by Ross Shuler. Its diameter is one inch, it cost $35 and was money well spent. I needed a few shims to time it with the top ports at 12 o'clock. After beveling the back of the brake, I sandblasted and then painted it. Moving back to the handguard, I drilled and tapped it to accept a Picatinny rail that I located at 12 o'clock. Onto this rail I mounted a US Optics level, which allows me to see and adjust the level before I pull the trigger. Some scope levels are scope mounted, but with my aging eyes, it works better to have the level further away, out at the end of the handguard. The scope I used was the Bushnell 3.5-21X with a Horus H58 reticle and .1 mil windage and elevation adjustments. The scope worked well except at one mile, where I couldn't dial out all the parallax. I had Todd take a look and he couldn't dial it out either. (Editor: Do it the easy way. Skip any one mile matches until the summer is over...)
My stock work is shown in the photo at right. The top knurled screw secures the vertically adjustable recoil pad in place. The bottom knurled screw secures the vertically adjustable toe in place. The paracord is the rear sling attachment point for HK style slings. The adjustable toe fits into the sandbag ears and can be adjusted up and down about an inch. What I like about a standard stock with the angled toe running up to the pistol grip is that you can make elevation changes by running the sandbag fore and aft. The down side is that during recoil, the muzzle rises as the stock moves back and down. With a flat bottom stock (that is, the toe of the stock running parallel with the barrel) the muzzle doesn't tend to rise as the stock moves to the rear, but it is necessary to change the bipod height or front rest height to make elevation changes. With an adjustable toe, you get the straight back recoil and it's easier to make elevation adjustments since you don't have to reach forward to adjust the height of the bipod.
I broke in the barrel, sort of, using a shoot one and clean regimen for the first five shots. Then I moved forward with "the Quest" – looking for the accurate load(s). With 142 Sierra MatchKing (SMK) moly coated bullets over 47 grains of H4831SC, I shot a three shot group of .41?. That looked promising so I loaded up five more rounds and shot a five shot group of .68? at 100 yards. Velocities ran from 2730 to 2757 fps with this load that is one grain under the max listed in the Hodgdon manual. I tried the same load with the second barrel and got slightly higher velocities.
Barrel #1 accuracy results: I fired about 50 rounds through this barrel and averaged .80 MOA three shot groups for all the groups, good and bad, at 100 yards. If I fired it, it's included in the average. No rounds were thrown out. The smallest groups were fired with the 142 Sierra MatchKing (SMK) bullets loaded .008? off the lands. The last group, a five rounder, measured .68? and clocked 2742 fps. That looked OK, but I still had time before leaving for Texas so I unthreaded Barrel #1 and threaded on Barrel #2.
Barrel #2 accuracy results: Prior to leaving for Texas, I fired about 110 rounds through this barrel, with an average three shot group size of .71 MOA. My best two groups were with the 123 grain Scenars (.21?) and the 140 A-MAX (.24?). Since this barrel shot marginally better than barrel #1 and it was time for the course to begin, I decided to take this barrel to Texas. I shot about 210 of the moly 140 A-MAXes at Canadian and have no complaints. Since I didn't clean the barrel at all while I was there, I shot a group at 100 yards when I returned to my home range, to see how the lack of cleaning affected the accuracy. That five shot group measured .72?. I consider that group size (≈3/4 MOA) to be typical for the run of the mill military and LE sniper rifle. I've seen better than that, but not very often.
Dies
While I was waiting for the barrels to arrive I got started on the brass and dies. The dies I started with were RCBS and Hornady New Dimension. I set up the full length sizers to push the shoulder back to SAAMI minimum minus .002?. By the way, don't change shellholders after you set up the dies or you might change the headspace. For my two shellholders, the difference is .002? and one shellholder makes firm contact with the bottom of the die, while the other does not. The Hornady dies reduce the shoulder diameter from .457? (fired) to .452?, and size the ID of the case mouth to .260?. The RCBS dies reduce the shoulder diameter to .454? and the neck to .260?. After working on barrels 1 and 2, I purchased the Lee Collet die set so that I could size just the neck. It initially sized the neck ID to .262?, but I polished the decap mandrel down to .260? to give the neck a tighter bite on the bullet and match the other dies. I like the Collet dies, and it's nice not having to mess with lube before and after sizing cases.
The Wind Course. Notice that the lanyards hanging at the bottom of the Kestrels are whipping in the wind. Cell phone photo courtesy of Todd.
The concentricity of my loaded ammo is typically .002? or .003?. The worst I've measured was .005?. I'm not saying that's great, I'm just sayin' that's what it is. By comparison, Federal's 308 Gold Metal Match averages .004? whenever I've checked it. I don't think I'll get the concentricity any lower without turning the necks.
Ammo
The brass (300 pieces) arrived in six 51-piece bags and was made by Remington. I started sorting them by weight, in .5 grain increments. What I ended up with was the following, shown in Table 1.
I checked them for length and trimmed those that were over 2.031?. Most fell in the 2.029? to 2.031? range. Then I chamfered the case mouths and deburred the flash hole. Finally I full length sized them all and primed them with Winchester WLR primers. I was going to buy GM210 primers but Sinclair was out and the nice guy that answered the phone said that he used the WLRs in his long range rifle. When I handload the ammo I keep the brass segregated in its half-grain groups.
I checked the jam lengths for the following bullets in barrels 1 to 5.
I do have two types of 140 grain A-MAX bullets, some older ones and the new AMP versions. The jam lengths and overall lengths differ between the old and the new. For example, barrel #3 has a jam length of 2.836? for the old 140 A-MAX and 2.866? for the new 140 A-MAX. The old A-MAX is 1.367? long and the new AMP A-MAX is 1.379? long.
Each barrel was checked for accuracy using six to eight different types of the above listed bullets. The Alpha Industries 10 round magazine that I use can handle cartridge lengths up to 2.89? so I can load all these rounds as far out as I need and still cycle them through the magazine.
I happened to meet Troy Lawton (AMU) at an ammo meeting. I asked him if he had any recommendations for 260 loads. He recommended H4350 and mentioned firing the 142 SMKs at 600 and the 107s or 123s at 200 and 300. I did use H4350 for my loads that I took to Texas. H4350 is part of the Hodgdon Extreme line of powders, known for their temperature insensitivity.
Canadian Adventures
We arrived at Accuracy First on a Monday morning, with the prospect of three windy days in the 70s, followed by a rainy or snowy day. As such, we decided to spend as much time outside the first three days and then have more classroom time on Thursday. Mr. Beaufort and I decided to mix our shooting between the school guns (LaRue 18? 308 OBR rifles with Horus Tremor reticles) and our own rifles (my 260 and his 338 Lapua Magnum) with Horus H58 reticles. With that plan in mind we headed to the 100 meter range and zeroed our rifles. This was my first exposure to shooting in real wind – not the gentle breezes of Virginia but the full blown winds of Texas. The wind blows dirt and sand into everything. That's eyes, ears, bolt, safety, magazine, pockets, ammo boxes – well, you get the idea. My safety became non-functional at this point due to blowing sand. The bolt release also became barely functional. We left the 100 meter range and headed out to one of the ranges to "true" our guns. The concept here is to shoot the gun at a distance where the bullet goes transonic (around 850 meters with the 308) and see what its drop is. You tell the computer what the drop is at that distance and it will adjust the velocity or BC to match what you just found. I trued the rifle at 1045 meters, where my come-up from the 100 meter zero was 9.5 mils. My bullet wasn't transonic there but it was far enough out to be useful. Using the environmentals of the time I told my Kestrel that my muzzle velocity was 2775, that my bore height was 2.91?, that the barometric pressure was 27 (IIRC), etc. and that it took 9.5 mils to hit at 1045 meters. It figured out that I would need a G1 BC of .64 for that to be true. Based on that, the Kestrel made a range card in 10 yard increments. Using a Vectronix Terrapin L5, we lased our targets or mil'ed them to determine their range and then the Kestrel told us our mil holds. At 790 meters I held 6.2 mils and hit one out of five shots. My hold at 475 was 2.5 mils, at 520 it was 3 mils, at 700 it was 4.8 mils and at 890 meters my hold-over was 7.3 mils.
Monday afternoon we grabbed the OBRs and headed to the Golf Course. Todd would tell us what "par" was for each station and then we would mil the target, determine our range and make a wind call. If the target was more than 600 meters away, Todd would tell us the distance. If the range was less than 600 meters, we had to mil the targets to determine their distance. The targets were either 12 inch steel circles or 12 inch circles on top of 16 inch steel squares. The OBR I was using had the Tremor reticle. Hash marks in .1 mil increments were used to determine how far away the target was. For example, a 12 inch plate that appeared .6 mils high (or wide) was 508 meters away. Once we had the range, we used the Kestrel to determine wind speed. Then we determined if the wind was full value, no value or somewhere in between. Based on that, we made a wind call. Todd had formulas for this, and the reticle had wind dots that helped us with our holds. At one location, Todd pointed out how the wind became audible at 16 to 18 mph. I hadn't noticed that – of course, I had my hard ears on. One, to protect my ears from a 338 with a muzzle brake, and two, to keep the wind from blowing off my cover. The first plate was a par 2 and I hit it on the second shot. The second plate was at 705 meters and was a par 3. I hit it on the third shot at 6 mils elevation and holding 7 wind dots into the wind. I think most of the stations were par 1 to par 3 and as I look at my notes I see some 4s and 5s. On a positive note, as I got to the end of the course, I hit the 743 meter target (a par 3) on the second shot. The last shooting location was at the top of a steep hill. We were encouraged to hear that the Marine Snipers ran from station to station. Twenty-five years ago I would have tried that, minus gun and gear, but those days are long past. So with all the speed of a glacier, I eased my way to the top of the hill and got one shot off – a hit – before the sun dropped below the horizon and my reticle disappeared into the darkness. That ended day one.
We headed to the Cattle Exchange restaurant, ate a trough full and then finished it off with bread pudding. For what it's worth – it's really not pudding – it's more like cobbler. I made a mental note that it took two Cokes to wash all the grit out of my teeth. Mr. Beaufort said, "I think I got a rock stuck in my moustache." I have no doubt.
On Tuesday we grabbed the OBRs in the morning and then traded them out for our personal guns for the afternoon Wind Course. (See photo 3). It's called the Wind Course for obvious reasons, and your score doesn't count unless the winds are at least 15 mph sustained. Our scores counted since we had a max wind reading of 37 mph. Your score is determined by getting 2 points for a first round hit on a target and 1 point for a second round hit. There are 15 targets (we only saw 13) located around the top 360 degrees of the hill. Max score is 30. The course record was set by Scott last year and stands at 17. I tied Mr. Beaufort with a whopping 6. I got a point on the 318 meter target, one at 467, one at 632, two at 530 and one at 450. The targets placed at 650 to 800 meters were completely safe. Scared maybe – from close misses – but safe. I wore some very fashionable goggles that kept my eyes from tearing up and getting sandblasted. I carried my gear in an Eberlestock Gunslinger pack (GS05ME) that has a rifle pocket big enough to carry the OBR or my Tak-MAK. It also carried my water, trail mix, rangefinder, Kestrel, notebook, sandbag, goggles and first aid kit. There's room for more than that but I was trying not to weigh myself down with a hundred pounds of lightweight gear. We left our shooting mats (5 lbs) behind for the same reason, not to mention that the steely eyed death merchants we were with didn't carry pads so we didn't want our lacy undies to show. Fortunately, the occasional hit waaay out there took our minds off the rocks we were laying on.
Wednesday was the day we went for The Mile Shot. We started out at some closer range targets before working up to 1609 meters (one mile). We shot at 340, 660, 688, 760 and 794 meters. Then at 1000 meters I held 9 mils and held 3.4 mils into the wind. At 1070 meters we found a 12 inch plate painted black. I hit it with a hold of 10 mils and 2.7 mils into the wind. At 1270 meters I held 14 mils elevation and 4 mils into the wind. Finally it was time to shoot into a different time zone/zip code. I lazed the target twice and got 1610 and 1611 meters. Mr. Beaufort went first, with his 338, shooting 250 grain BTHPs. His elevation ended up being 18.5 mils. By contrast, we asked the OBR shooters what they were holding and they were at 34 mils. After he whacked the steel (12 inch circle over a 16 inch square) a few times, it was my turn with the 260. I came up 13 mils on the elevation dial (I only had 14 mils left on the dial) and then held 8 more mils on the reticle. No joy – no puff of dirt could be seen. Hold 9 mils and let fly. No joy. Hold 10 mils and let fly. Yeah – a puff of dirt marked the impact. From there I was able to adjust for the wind and start hitting on and around the steel. In total, I hit the steel three times with the 260 (witnessed). I connected with holds from 23 to 24 mils and 2 to 4 mils into the wind. The parallax at the bottom of the field of view in the scope was running from the top to the bottom of the target. That plus the changeable wind, plus my belly shooting (dis)abilities, plus the elevation variations due to muzzle velocity variations (about 23? worth of vertical between 2771 and 2789 fps) and I'm amazed that I ever hit anything at that distance. After hitting the target with the 260 I gave the 338 a try. On the tenth shot I rang the steel with one of the 250 grainers. I got back to the hotel and wrote in my notebook, "Good day in Canadian. The wind was 16 mph, which sure beats 37. No grit in my teeth today. I hit the mile target three times with the 260 and once with the 338. I had beef quesadillas and bread pudding for supper and a lady (Dianne) left cookies for us at the hotel." Pretty friendly locals. Thanks, Dianne.
The ballistic solver that I used was the Kestrel 4500 NV Horus. It combines wind speed, pressure, temperature, etc. with a PDA. You can call up a range card that calculates holds for elevation and windage in 10 yard or greater increments. It's a really sturdy unit that put up with all the blowing dirt and kept ticking. The battery life is also very good. With the "environment" turned on, the unit constantly updates the meteorological data and changes the range card to account for the changes. You can enter and save a bunch of guns in memory and then pick the one you're using. I entered 260 Rem, 2775 fps, .60 BC (G1), 140 grain, .264 diameter, 100 meter zero, 2.91? sight height and right hand 1:8 twist barrel. You may have noticed that I said the effective BC was .64 earlier in the article, which is true, but I had to lower it to .60 to agree with the come ups out to a mile. Apparently the transition to subsonic flight made the difference. Or something(?). Hey, if I had all the answers, I'd write a book.
Barrel #3 accuracy results: Getting back to work after I returned from Texas, I installed barrel #3 and shot about one hundred rounds through it – averaging .80 MOA for its three shot groups. The 130 Norma shot a .55? three shot group at .020? off the lands. A follow on five shot group measured .65?. The meplat on that bullet sure is small. The best group with this barrel, a .24?, was with the 142 SMK over 38 grains of Varget, at 2638 fps.
Barrel #4 accuracy results: I fired 120 rounds with an average three shot group size of .81 MOA for all the groups. My best groups include the 140 Berger VLD at .37?, the 140 A-MAX at .35?, the 142 SMK at .29? and the 123 Scenar at .20?.
Barrel #5 accuracy results: Up until this barrel I felt that the performance of the barrels was pretty similar, running .7 to .8 MOA, and I wasn't expecting #5 to be much different. Then I started shooting this barrel. The second outing I put up a sheet of paper with eight orange dots to record my eight three shot groups. I loaded 39.5 grains of Viht N150 under various seating depths of 139 grain Scenars, 140 grain A-MAX bullets and 142 grain SMKs. I averaged .44? for the eight groups. The best group was .20? with the A-MAX bullets. These were the old style, pre AMP bullets. For the next day's outing I loaded five rounds of this same load plus some other new loads. Scott hadn't shot a 260 so he volunteered to do the shooting. I showed him the .20? group and told him that all I needed was nothing less than his absolute best shooting. I was watching through the big Unertl spotting scope as he punched out a .34? five shot group. Yep, that'll work. I think I'll hold onto this barrel.
The 140 grain A-MAX is a target bullet, but that didn't stop me from thumping a block of 10% ballistic gelatin with it at an impact velocity of 2751 fps. The bullet penetrated 13 inches, expanded to .66? and weighed 63 grains. The bullet expansion started immediately – no neck length. I also shot a few other bullets into the ballistic gelatin with the photo and penetration results shown below.
Contacts:
Accuracy 1st, Inc.
[email protected]
Eberlestock packs
www.Eberlestock.com
877-866-3047
Horus reticles and Kestrel ballistic solvers
www.horusvision.com
650-588-8862
Vectronix
Laser range finders
www.vectronix.ch
703-777-3900
