It's not smart to use a slip over barrel adapter for a can
Most barrels, especially rugers, are not concentric OD to bore. These reference no alignment to the bore.... plus using a set screw will further tilt the suppressor from center unless its a perfect slip fit.
Think about the tolerance band on the OD of a paclite..
. Probably whatever the extrusion is; +/-. 005
I concur, slip ons not good.