Vertical Stringing on an AR

[ReservoirDawg10]

My assumption is something is off with the rifle or the shooting technique. If the barrel is shot out, I would expect more of a shotgun pattern, not vertical stringing. AR's are much more susceptible to varying forces on the forearm, especially if it isn't free floated. How were you shooting? What kind of set-up? 10 inches of stringing is still excessive, especially at 25 yards, so something mechanically is messed up somewhere if I were to guess.

 

[RobsG]

I didn’t even read the original post, I answered the subject question. I have to agree, something else is wrong with the gun. A shot out barrel just results in poor accuracy not vertical stringing like mine (heat, not ammunition velocity induced btw). I bought 5 M1 Carbines from the CMP in 2009 and even though the barrel muzzles gauged “3”, they were pretty bad accuracy at 50 yards. If you are stringing 6-10 inches, you have a problem with your setup.

 

[GeauxLSU]

Vertical stringing is normally caused by ammo. That is to say inconsistent velocities.

Sorry. Missed that it was TEN INCHES at 25 YARDS. Unless you are throwing the ammo, it's not the ammo.

 

[BigMike]

Im at a loss. I am not a builder so I have no idea what could be wrong with it. Its a buddies gun and he knows what he is doing with ARs. We were shooting federal ammo. I checked for something stuck in the barrel and chamber, pulled apart the bcg, etc. After thinking it through, I'm betting the barrel is bent, and the heat from firing is making it walk all over the paper. Starting from a cold gun and only firing three shots should not make it spread out like that unless something is going on with the barrel. Its a spikes receiver set, midwest handguard, and the barrel is the FN, but used out of a machine gun.

 

[rOmiLaYu]

If you're getting ten inches of vertical stringing at 25 yards, something is big time wrong with the rifle or the shooter. Sounds like the barrel is on its last leg, but even that shouldn't cause the degree of malfunction you're seeing. In my experience, vertical stringing usually has more to do with the shooter than the rifle.

 

[BigMike]

If you're getting ten inches of vertical stringing at 25 yards, something is big time wrong with the rifle or the shooter. Sounds like the barrel is on it's last leg, but even that shouldn't cause the degree of malfunction you're seeing. In my experience, vertical stringing usually has more to do with the shooter than the rifle.

With two different shooters who are shooters getting the same result, we eliminated that.

 

[rOmiLaYu]

With two different shooters who are shooters getting the same result, we eliminated that.

I don't you know you from Adam, so forgive me if this is pointed but, it's impossible to eliminate operator error. And I'm not sure what you mean by being a "shooter," but I've known plenty of guys that have been shooting longer than I have that still have flaws.

Now, if it's an issue of only this one AR stringing, I'm more like to be inclined to be it's the rifle and not the rifleman. Having said that, though, I can't think of a single thing that would give you that level of malfunction and still allow the gun to be functional. The only thing, and it's a way out there thought, is that the barrel isn't seated correctly and the nut is cross threaded or improperly torqued and that is creating some bizarre harmonics in the barrel.

 

[ReservoirDawg10]

I don't you know you from Adam, so forgive me if this is pointed but, it's impossible to eliminate operator error. And I'm not sure what you mean by being a "shooter," but I've known plenty of guys that have been shooting longer than I have that still have flaws.

Now, if it's an issue of only this one AR stringing, I'm more like to be inclined to be it's the rifle and not the rifleman. Having said that, though, I can't think of a single thing that would give you that level of malfunction and still allow the gun to be functional. The only thing, and it's a way out there thought, is that the barrel isn't seated correctly and the nut is cross threaded or improperly torqued and that is creating some bizarre harmonics in the barrel.

I'm with you. I can't imagine what turns a rifle to string like OP is saying, but the groups do not shotgun pattern.

 

[CBeck]

I don't you know you from Adam, so forgive me if this is pointed but, it's impossible to eliminate operator error. And I'm not sure what you mean by being a "shooter," but I've known plenty of guys that have been shooting longer than I have that still have flaws.

Now, if it's an issue of only this one AR stringing, I'm more like to be inclined to be it's the rifle and not the rifleman. Having said that, though, I can't think of a single thing that would give you that level of malfunction and still allow the gun to be functional. The only thing, and it's a way out there thought, is that the barrel isn't seated correctly and the nut is cross threaded or improperly torqued and that is creating some bizarre harmonics in the barrel.

I’ve seen some pretty bad shooters but 40 MOA at 25 yards would be impressive.

 

[BigMike]

I can drive finish nails, especially at 25 yards. I think I'll take a case of beer over and yank it apart and see if something is binding.