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Posted: 11/20/2008 2:54:10 PM EDT
I have the typical slant brake and also a U.S.-made AK-74 style brake.

I've shot with the 74-style brake a couple of times, and it seems that the gun shoots very low when I use it –– I'm talking about 4-5" low at 15-20 yards. With the slant brake, all is well.

I haven't had a chance to do a real scientific test –– a few shots, switch brakes, a few shots, etc. I've only used a single brake on each range trip.

There's no evidence that the bullet is hitting the brake.

Is this possible? Or is it just my wild shooting? Or maybe my pencil-pushing office arms just can't lift the heavy 74-style brake up high enough??
Link Posted: 11/20/2008 3:35:03 PM EDT
Link Posted: 11/20/2008 3:38:18 PM EDT
Wouldn't the bullet have left the barrel by the time the compensator starts working?
Link Posted: 11/20/2008 3:51:12 PM EDT
[Last Edit: 11/20/2008 3:52:01 PM EDT by Mad_Pick]
Originally Posted By VA-gunnut:
If it were a greater distance I would say that it's the recoil causing the round to hit higher. I'd be shocked if you were getting that much rise at 25yds just from recoil.

Are you shooting from a bench?


Yes, I was shooting from a bench. That said, though, I wasn't doing my best shooting . . . so I haven't ruled out "me" as the cause.

However, since it happened so consistently on two different range trips I wondered if this was a known phenomenon.

Also, this is slow shooting –– not multiple shots where I'd get muzzle rise from the previous shot.
Link Posted: 11/20/2008 4:14:07 PM EDT
Originally Posted By Mad_Pick:
I have the typical slant brake and also a U.S.-made AK-74 style brake.

I've shot with the 74-style brake a couple of times, and it seems that the gun shoots very low when I use it –– I'm talking about 4-5" low at 15-20 yards. With the slant brake, all is well.

I haven't had a chance to do a real scientific test –– a few shots, switch brakes, a few shots, etc. I've only used a single brake on each range trip.

There's no evidence that the bullet is hitting the brake.

Is this possible? Or is it just my wild shooting? Or maybe my pencil-pushing office arms just can't lift the heavy 74-style brake up high enough??



This is very common The rifle seems to be zero'ed with the slant brake. The Heavy 74 style brake is reducing muzzle rise, thus lowering the zero. This also depends on the person shooting and how the rifle is held/shot. I recently had to re-zero my Aimpoint from using a tantal muzzle brake to a FSC47 brake. 25 yrds i was 1.5 inches low. 4-5inches is alot imo.

gl
rube
Link Posted: 11/20/2008 4:18:53 PM EDT
Muzzle Brake - Affects point of impact?

You might find this interesting..

Not too long ago I assembled an unissued Romanian G kit on a NoDak receiver, with the Tapco slant-style brake. The Tapco brake can be installed one of two ways - ostensibly to adapt for right or left-handed shooters. I am a RH shooter, but I accidentally installed the brake as for a LH shooter.

The gun shot WAY left at 25 yds (the only distance where I can still see the target). When I say 'way left' I mean out in the 5 ring of a standard 100 yd small-bore rifle target. When I discovered the error, and switched the brake over, it shot dead down the center.

Also, FWIW, this gun shoots low.. that is, I have to set the rear sight to the 'battle' setting to get POA.. that is, sights aligned with the center of the bull to hit the bull @ 25yds. I might remove the brake and see if there is any effect.

-L
Link Posted: 11/20/2008 4:22:07 PM EDT
Yes, changing what you hang off the muzzle will change POI.

My AK gives the tightest groups with either tha muzzle nut or the AK74 brake. The flash hider opens up the groups a bit. All three devices give me a different POI, separated by about 5", at 100 yards.

BSW
Link Posted: 11/20/2008 6:29:58 PM EDT
Thanks for all of the input, guys.

I guess I need to make a decision regarding which brake to use, stick with it, and re-zero as required!

(Oh . . . and practice, practice, practice!)
Link Posted: 11/20/2008 6:59:31 PM EDT
I have an AMD 63 that came with a slant brake. It shot way too high at 50 yards and to adjust the front sight to make it zero, made the front sight too lose and wobbly. I tried several other flash hiders and found one that made poi about 8" lower at 50 yards and made it much more accurate to boot.
Link Posted: 11/20/2008 9:59:53 PM EDT
Originally Posted By TexasPatriot:
I have an AMD 63 that came with a slant brake. It shot way too high at 50 yards and to adjust the front sight to make it zero, made the front sight too lose and wobbly. I tried several other flash hiders and found one that made poi about 8" lower at 50 yards and made it much more accurate to boot.


Eight inches lower at 50 yards, eh? Well, that's pretty close to what I'm seeing!

Thanks, that makes me feel much better!
Link Posted: 11/21/2008 2:56:05 AM EDT
Originally Posted By briansmithwins:
Yes, changing what you hang off the muzzle will change POI.

My AK gives the tightest groups with either tha muzzle nut or the AK74 brake. The flash hider opens up the groups a bit. All three devices give me a different POI, separated by about 5", at 100 yards.

BSW


I've noticed that the POI will change. The slant brake causes the POI to move about 3" at 50 meters if the rifle is zeroed using a birdcage FH, which is consistent with your results.

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