Gunsmithing Point of impact change

[ChadJamesR]

I'm working on loads for my AR15 and noticed that when the Ops Inc muzzle brake is on the rifle, it shoots nearly 3" lower at 100 yards then with the brake off. The horizontal stays the same.

I know when you remove a muzzle brake that you can expect a point of impact change, but is this much change normal? Would this be an indication that the brake is not installed correctly?

Thanks,

 

[Hellbender]

Re: Point of impact change

Not if the groups are good.

 

[Hateca]

Re: Point of impact change

I could be the threads were not cut true to the bore but you won't be able to tell that.

The brake could be installed correctly it could be the amount of torque you are applying to the brake when you tighten it down. Torque on a muzzle device can change POI, a lot of torque can actually change the diameter of the bore at the muzzle.

 

[jrpilot]

Re: Point of impact change

I have seen a brake change the POI by 2-3in a few times. +1 with Hellbender.

 

[edwin907]

Re: Point of impact change

Chad, how does it do with the suppressor (if you have it yet)?
I get almost no shift with/without the suppressor on my 18" SPRs (Krieger, Douglas) and even less with the 16" (Krieger).
Since it is a brake and does a pretty good job on controlling muzzle rise I would expect a POI shift.
I haven't shot any of them without the OPS in so long (years ago, Mod0, I think it shifted directly down to 6 O'Clock), I'm not much help.

 

[ChadJamesR]

Re: Point of impact change

Unfortunately I don't have any suppressors yet. The Ops Inc muzzle brake is the dual chamber type not meant to be used with a suppressor.

I was having problems with the brake coming loose at first and my groups going to crap but this last time I went out I tightened it down well and used blue Loctite. What torque should be on the brake and is blue Loctite good to use or do you suggest something else.

This last time out with 69gr Nos CC bullets and IMR8208 powder I was getting anywhere from .4" to 1.1" at 100 yards using different powder loads. The free bore was cut too long on this chamber and I have to jump the bullets about .04" to keep them mag length. I believe these bullets typically like a .02" jump to the lands so I think my accuracy is limited unless I load single rounds.

Thanks,

 

[Outsydlooknin75]

Re: Point of impact change

Blue loctite is not what you want .... call around and see if someone has some "rocksett" Chris Hunt might have some. Use rocksett and not the loctite.