If something ain’t broke there is a strong argument to not fix it. Fortunately for .50 Caliber match shooters though, the team at ArmaLite must have played hooky the day they learned that in 2nd grade. Even though their ArmaLite AR-50 has already been a strong competitor in national matches, they decided that it had to be improved for the most elite competition shooter.
Guns in general have to be built with tolerances that reflect differences in manufacturing tolerances for ammunition. Things like case head thickness, width at the bottom, width at the shoulder, shoulder angle, and even brass thickness can fluctuate sometimes several thousandths of an inch. There are specifications for cartridges put out be the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI), but some play is assumed when you cut a chamber for a rifle in a standard caliber.
To competition shooters these tolerances can be a headache because if you use “match” ammunition, it is all one size, and if the chamber of your rifle has a lot of sloppy “tolerance” room, the cartridge can be canted in the gun to one side or the other of that several thousandths of tolerance without you being able to control it. The same is true if you full length re-size a round in your .50 caliber reloading press. The resulting cartridges will be perfect SAAMI specs.
National Match rifles don’t have this tolerance built in. The downside is that you can’t just order a case of surplus ammo on the internet for them and expect them to always fit your gun. But the upside is that you have a perfectly reamed chamber that will exactly match your match ammo, or your full length re-sized reloads. So if you miss, or your score isn’t what you want it be, you can assume it was your fault and not the fault of the gun.
Now, you may be wondering, if this is true, how is it that people have been winning matches with these standard chambers in AR-50 rifles. There is a caveat to this explanation. Many competition shooters hand load their own cases. Your chamber, if it is not a National Match chamber, is unique, and once you fire a round of ammo in it, the pressure will shape that brass casing to exactly match your chamber. If you then full-length re-size that case, it will no longer match your gun, but if you only use a neck sizer to expand the mouth of the case to hold your bullet, the rest of the case will stay the size of your chamber, and have zero tolerance. It will be as if the chamber is reamed exactly to the ammo you are using.
The AR-50 National Match gives you the option to use pre-made factory “match” ammunition that will fit just as perfect, or theoretically just as perfect. It also gives the hand loader the ability to full length re-size fired cases, which can have its benefits (outside the scope of this article). Again, don’t forget, a National Match chamber may not fit some surplus ammo that you may find for sale, so don’t buy one of these guns thinking that it is the “extreme accuracy” version of the gun suitable for all shooters. It actually is the extreme accuracy version, but specifically for competitive shooters in a controlled environment with standardized ammo. If you are buying a .50 just because you can, and you hope to shoot it for fun and keep it “just in case,” you are better off with a standard AR-50 chamber that will still yield better accuracy than 99%+ of shooters can shoot.
This new ArmaLite comes with some other non-standard features as well. ArmaLite has built a new skid plate system for bench rest shooters to allow the gun to sit flat easily and naturally slide with recoil. This slide plate system will also be available to retro-fit existing guns. It has a match trigger group, and the barrel on the National Match is three inches longer than the standard 30″ The MSRP is $4,230.