Your pellets are clipping the silencer
use a straight rod same size as your bore to check alignment.
Depending on the silencer you may have to strip it to check for marks where the pellets have clipped the internal baffle .
I have found swarf from machining to be a problem in a few before stuck between baffle plates ,or the cap on the mod may just need tightening to center the internal baffles .
Sometimes you need to check the machined face of your muzzle if it is screw fit as burrs can throw them out of line when screwed up tight .