M1A super match, loose flash hider.

[Pop]

I bought a springfield FS for my norc and it was quite loose in the spline. I've peened the barrel, but there's only so much you can do and there still have a little bit of wiggle. I have a castle nut plier so I can tight the screw enough so it doesn't move. Not sure if this still affect accuracy. I havn't try the JB weld fix yet,butOP you could try filling your spline with JB weld and slinding your FS unit in so it marry with the spline. Just make sure it doesn't get stuck there

If you use a release agent on one of the surfaces (clear shoe polish works) you might be able to effectively "bed" the flash hider without bonding it permanently to the barrel.

 

[Dake21]

Interesting, I have some clear show polish at home. When I get back I'll check that out.

 

[Glock4ever]

I am not sure if it is harmonics or if the FH was touching the projectile as it passed through or something else but the rifle's practical accuracy was definitely not as good. Sometimes we could hit and completely miss other shots we would typically be 4-5 hits/5 shots and it was down to maybe 2 hits per mag. After tightening the FH right back to 4-5 hits per mag.