“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).
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.