Odd FAL performance

[stubbicatt]

I have a buddy who is really into FALs. Thinks they are the greatest, an opinion I don't share.

Anyways.

He shoots Black Hills 168 grain match ammo through his high dollar rifles, and finds that he gets a huge zero shift from ball ammo through his FAL. Using a good scope, allegedly firmly attached to his FAL, he zeros his rifle with Portugese surplus ammo. Breaks out the box of BH, and his zero shifts up and right about 3". The grouping is not good at all, grouping larger than does his ball ammo group. To be sure it isn't a scope shift or something, he recommences with the ball, and the shots fall in the ball grouping.

That the ammo shoots to a different point of aim doesn't surprise me as much as does the fact that the group is not good at all, like 6" or something.

Oddly, his custom built M14 shoots tighter groups (no surprise) and the zero shift is only upwards an inch or two, and the groupings with the BH are quite tight, as one would expect.

He asks me what is causing this sort of aberrant performance in the FAL, and I don't have an answer. Is it possible that the FAL has a slower twist barrel that won't stabilize 168 grain bullets? What gives here?

Thanks.

 

[Taurus 617 CCW]

Twist rate could be a factor. Have him try FMJ's and BH's with the same grain weight. If that doesn't fix the problem try going from a secant tangent bullet to an ojive tangent. Hornady manufactures a longer bullet, where Nosler manufactures a more rounded one. That may have something to do with it. My FAL has consistently performed with just about any ammo I put through it but I haven't benchrested it for accuracy yet. Hope that helps.

 

[USSR]

He asks me what is causing this sort of aberrant performance in the FAL, and I don't have an answer. Is it possible that the FAL has a slower twist barrel that won't stabilize 168 grain bullets? What gives here?

First, there is no problem with the 1-12" twist of a FAL stabilizing a 168gr bullet. As for the 168gr bullets shooting higher, heavier bullets tend to shoot higher due to a lengthening of the time the heavier bullet spends in the barrel. I would suggest that he tries a couple things: First, completely clean the barrel prior to using the BH ammo; and two, optimize the gas setting for the BH ammo.

Don

 

[Robert]

Zeroing with one type of ammo and then switching to another will produce different groups. The Black Hills Ammo is top notch, the surplus not so much. From what I have seen surplus ammo is about 147 grain bullet weights. Almost all the surplus ammo I have shot is very dirty which could be fouling the barrel enough to throw the Black Hills ammo off. The difference in weight could be the issue as could the fouling. I agree a swab of the barrel between ammo types may be needed. And as much as I love my FAL, one must keep in mind that it is not a match grade firearm. It is field grade, meaning I can hit whatever I am aiming at out to a given range, but she may well never produce one hole at 100 yards. It is an excellent battle rifle, not a match rifle. And you are right it is not odd that a custom rifle shoots tighter groups.