I've got a multimount on a 9mm SBR with a 3 lug barrel. Without the silencer, the gun is pretty accurate at 25 yards and it's zeroed perfectly. I stick the multimount on, and the first few shots are pretty close to the original POI, not a lot of POI shift.
However, as the can starts to heat up over multiple shots, the POI starts to "walk" and groups open up significantly. It mostly moves upwards, up to a foot high at 25 yards, and the group opens up to over a foot at 25 yards (compared to 2-3 inches with no suppressor). Has anyone else noticed a similar problem with the multimount, or other aluminum 9mm cans on SBRs? Anything I can do to correct this?
I'm not getting any keyholing, or baffle strikes, so the gun/ammo combo doesn't seem to be a problem. I've tried indexing it in all 3 possible notches, etc. I've tried adjusting my zero to work with a hot suppressor but the group just opens up too much for that to be practical.
Thanks for any thoughts/advice.
Originally Posted By CARSINC:
Do you have a lathe handy?
My guess the bore/ tube is out of round in the can.
google jail break mutimount.
I would guess that it warms up and bullets are touching the baffles.
gemtech will fix this.
I don't have a lathe. I can call Gemtech and see what they think. I wasn't sure if it was a defect, or some type of issue with an aluminum can on a high volume gun (or something else I'm not realizing).
I have heard of a certain company that jailbreaks cans that have seen quite a few gemtechs with non concentric bores causing problems like this.