Suppressors Specwar accuracy issues

[flyfisherman246]

I have a very high quality ar15 upper built by a well known smith. I have tried every powder and bullet combination trying to get this thing to shoot well and its always hovering around an inch or a little over at 100 yards. But its never really consistent. Some groups are a little better and some are quite a bit worse. For whatever reason today I decided to take the spec war 5.56 can off the 3 prong flash hider and see what happened. I put the next 5 shots into about 1/4". Then I tried it again and shot 10 shots somewhere around 3/4". So this shows there is nothing wrong with the rifle, shooter, or ammo.

I do have this barrel threaded 5/8x24 and using a 7.62 .30 cal flash hider. Could that be causing the issues? I also have a custom built .223 bolt gun that I am using a 1/2x28 muzzle brake on and the suppressor doesn't effect accuracy at all on this rifle.

I have an adjustable gas block on this rifle and changed the gas setting for optimal performance between suppress and unsuppressed.

Has anyone seen this before? It has been confirmed now that my rifle shoots great without the can and just the flash hider, but once the can goes on everything opens up big time. Any ideas of where to go from here?

Thanks

 

[Badfinger]

Try it without adjusting the gas block, leave it open. My AR will do one hole groups using a 7.62 Specwar. I wonder how concentric your threading is to the bore? That could make a difference.

 

[smokin.338]

Barrel harmonics is coming into play... sometimes there's just nothing you can do !