Muzzle devices affecting accuracy

[flyfisherman246]

Maybe some of you read my thread asking why the ar10 was shooting one hole groups with a thunderbeast ultra 7 but then 2-3" with a silencerco muzzle brake and bare muzzle. This was when 175/178 grain loads. I then tried 168 grain handloads and all 4 loads with two different powders were around 1/2". I thought the problem was fixed. I failed to mention that I shot those 168 loads with an apa gen 2 little bastard. I went out today to confirm a 168 grain load with the silencerco muzzle brake and it shot about 1.5". I then tried it was the little bastard and it put 5 shots about 3/4". I then shot it bare muzzle and it was about 2.5". How is this thing so picky with muzzle devices? If anything it should shoot bare muzzle, but that shoots the worst. I don't understand what is going on with this thing.

For example, I have an lmt with a bartlein blank in .260. It doesn't matter what you hang on the muzzle, or anything at all and it doesn't really matter what bullet or what powder you shoot through it. It all shoots anywhere from decent to amazing.

This is a pretty stiff barrel. It is a bartlein blank tapered from a 2" straight chamber to .950 until the gas block and a .750 gas block. It is intermediate length gas tube and 16" barrel. Why is this so picking? Has anyone run into this before and what was the solution?

Thanks

 

[hlee]

The weight of the muzzle device can act as a "barrel tuner" and change the harmonics of the barrel. Sometimes for the better, others for the worse. Work up your handloads with the muzzle device you intend to use.

 

[Huskydriver]

Harmonics....

 

[flyfisherman246]

I understand how the weight of a device out front would effect the harmonics of the barrel, my concern is how differently the barrel shoots with different types of brakes. I have never seen it make that big of a difference before this barrel. Typically on other rifles it doesn't really seam to matter what is on the front, if anything at all.

I'm worried there's something going on with this barrel. Has anyone seen differences this big before?

 

[shax2lex]

I agree with them. Harmonics. Maybe get a thicker barrel?

 

[theLBC]

thanks for the details.
not because i know jack, i just want to try remembering things and regurgitating it again later if needed. input hog.

at this point, i would suggest calling barrel company (as they seem to suggest) and ask if they have seen this before.

 

[rpoL98]

from what I understand, if you overtorque the MD, it can affect the bore dimensionally. "Hour-glass" effect.

 

[oldfatguy]

Different muzzle devices make the barrel different. One load dose not fit all. Work up your load with the device you will be shooting.

OFG