[Reagan]

Changed out my stock SR556FB flash hider to an AAC Blackout and it appears the zero on my Troy BUIS and my Burris AR332 moved 3" right and 3" down...with 1-1.5 MOA groups....
I'm thinking the FH changed the muzzle pressure or altered it somewhat....I re zeroed both and they seem repeatable....
Used all the same rounds (xm193) and didn't over torque the FH ......
Any opinions... Would be appreciated...this really surprised me!

 

[Reagan]

No opinions??? Has the gov surveillance have everyone hunkered down?

 

[Blaze]

I want to give one. But I have no experience with A SR556

 

[ArizonaHeat]

Haven't changed out the flash suppressor on my 556 yet. So I don't have any solid help for you. Being that is a blackout fs the internal diameter should be larger slightly that could be the cause?? In any case that fs looks sweet got me eyeing the ugly birdcage on mine thinking it might be time for a change.

 

[bhale187]

I can't think of any explaination for that.

Is it possible the forearm rail moved while you were doing the install?

 

[phideaux]

In my mind, I first thought of a harmonic change in the barrel.
Sometimes ,any changes to a barrel will have a consequece.

I have a Mosin Nagant that changes POI ,depending on whether the bayonet is fixed or not, it affects the harmonics of the barrel and the pressure equalization on the bullet as it leaves the barrel and passes over the blade. I dont know if thisis ascientific fact or not...

but I do know the POI changes.


Jim

 

[bhale187]

I thought a disruption of the harmonics would just throw the bullet's MOA off, I didn't think it would maintain MOA but change POI, weird.

 

[phideaux]

I thought a disruption of the harmonics would just throw the bullet's MOA off, I didn't think it would maintain MOA but change POI, weird.

I know what your saying,and it is wierd,

But that Mosin is an accurate shooter and it does change POI when I fix the bayonet, and it will consistantly hold that new POI.

Im wondering if thats the case with his new muzzle brake, who knows, but it is an interesting developement.


Jim

 

[Reagan]

Interesting feedback, thanks....I'll see if the POI is repeatable the next time out....I hope so, I could live with it re zeroed....if it's off again.....I go mad and have to put the stock FH back on ....and go round and round....thanks again!

Update: after googling "new FH and POI" I saw a good response on an old forum post...he suggested that the new FH may create different turbulance to the exiting gasses @ the muzzel crown and it should be repeatable after re zero....in fact his POI was off 12" @ 100 yds.....
You think the manufacturer would warn or suggest that to you.