I have a B&T Rotex Print X 556. I also have a surefire RC3. I have one gun that absolutely HATES the Rotex. I mean, insane, trash groups.
On myColt EPR 11.5… It will shoot nice groups w/55 or 77 at 00. Consistent POA/POI. If I put the Rotex can on it the groups go TOTALLY INSANE. OK, so it must be the can. However, If I swap on my RC3 the gun goes right back to shooting Consistent POA/POI.
However, my OLD Colt commando upper I have been shooting for 10 years and has 8k plus rounds through it. If I shoot it with RC3 It is good but it also shoots nicely with the Rotex. Obviously, the zero shifts since the Print-x is way bigger but it shoots consistent groups, tight groups.
SO WTF? Both guns have the exact same surefire FH. Obviously, the one on my Old upper is beat to shit, but it is the same part.
Why would the rotex open up the groups like crazy on on 11.5 and not on other. Any possible solution? And let me be clear. I am saying 55 grain PMC will shoot a 5 shot group inside a fist when shooting casually with either rifle with the RC3. But the Rotex opens up the groups to completely inconsistent on the EPR. I am talking about pizza box sized stuff you wouldn't accept on a counter-bored mosin you pulled out of a pond.
The only thing I can think of is some sort of interaction between the B&T surefire mount and the newer FH on my EPR. But I can't figure it out.