Great but... - Seekins Precision AR ATC Muzzle Brake

I put this on a new Sig Cross. The gun is only about 6.5 lbs, so it has a little kick...or jump in .308 cal. This muzzle device completely took care of that rise, and the recoil must be about half now. Also, I didn’t notice an increase in noise like you get with some brakes. It looks great too, but I had a couple minor problems (could just be my gun idk). First the locking nut didn’t seem to thread far enough down, but I did get the break on and clocked as closely as I could. The brake seems fairly tight, but I didn’t want to over tighten it. The biggest problem I had was my groups moved around and opened up some...while not awful, it was definitely noticeable. I will keep trying, and maybe see if some other ammo won’t shoot better. The brake doesn’t appear to be moving while I’m shooting. I thought about removing the brake and trying a couple groups without it, but decided to wait. I would definitely recommend this to cut recoil and muzzle rise...but you might loose a little accuracy.