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
FWIF, I believe Volquartsen sells a slip on device for the MK III...
Also, my favorite part of the EBay add:
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