Shot my P220ST suppressed for the first time using a factory SIG threaded barrel and Rugged Obsidian. I was a bit surpised by how much blowback I had in the face. I had noticed before cleaning the gun there is a large clearance cut in the slide where you can see straight through the barrel. I would assume that is where most of the gas is coming from.

This gun was purchased circa 2003 and has a West German frame, with US slide. Internal extractor. Is this gap as large on newer P220 models, and does anyone else have blowback concerns on their P220? The only other .45 I have shot suppressed was an M&P and it was very pleasant.

Dunno specifically about the 220, but I've found blowback to be very ammo specific. Try another brand and see if it's any different.