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p35bhp55 03-30-2013 02:09 AM

Muzzle Brake changing POI
I installed a Precision Armament M11 on a Bushy 308 ORC. The rifle was sighted in well with the POI about 2 inches above the POA at 100 yards. The rifle was in a vise when the A2 hider was removed there were flats on it to aid in removal. The M11 was threaded on it is snug not tight because I haven't ordered the proper shims. When I test fired it the POI had went down in a straight line exactly 5 inches.
The scope or rifle wasn't bumped during my work and the scope adjusted up and stayed put, it's hard to imagine the brake changed the bullet flight that much but that's the way it seems.

c3shooter 03-30-2013 03:20 AM

Believe it. different weight, isn't it? Changed the barrel harmonics. Browning uses a sliding weight to tune POI on some of their rifles.

jp_over 03-30-2013 02:57 PM

I had a muzzle brake installed on my 375H&H - the gunsmith said I'd have to sight it in again and he was right. I think you lose some velocity with a brake but, regardless of the reason, it can change POI.

p35bhp55 03-30-2013 04:38 PM

I'm a believer now just shocked at how much it moved at that range.

jp_over 03-30-2013 04:41 PM

Indeed - it would be interesting to see FPS measurements before & after the brake.

c3shooter 03-30-2013 04:49 PM

It's not just the speed of the bullet. Barrel whips a tad when you shoot. Bullet HAD been leaving barrel on an UP swing. Different weight on the muzzle, different vibration pattern- bullet now leaving on a DOWN swing. You can't see it- too fast for the unaided eye- but the vibration is there. Trust me.

MattShlock 03-30-2013 05:26 PM

5 inches seems like alot though.

Almost always the pattern opens up a bit too. Guns without muzzle devices are simply more accurate. Forget the proper torque for installing the device for the moment. There is backpressure that affects accuracy. The change could also be due to some related, unbalanced, force.

I like the Micor breaks because the slots are angled to match the twist of the rifle you put them on and the escaping gases are most efficiently vented. OMG, accuracy-wise, it's like there's no muzzle device on the gun but the Micor works better than standard issue for flash suppresion and at least as well on muzzle flip!

JonM 03-30-2013 05:45 PM

muzzle brakes suppressors flashhiders have no effect on velocity. that only happens in call of duty

triggerjob 03-30-2013 05:55 PM

I think your brake is off center on your barrel. Take the brake off and look into it and see if any lead or copper is shearing off inside of it.

You replaced a shorter flash hider with a longer muzzle brake. It could be your barrel end threads aren't centered to the bore, or the same thing could be wrong with the brake, occasionally both are off.

purehavoc 03-30-2013 05:57 PM

My buddies long distance target .308 is dead nuts with his custom hand loads . He put a brake on it and it would shoot about 15" high with the same ammo even in a shooting jig he uses to sight stuff in with .. Take the brake back off and its right on . I though that was pretty crazy that it was off that far .

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