I've run thousand's of 20ga. target loads through my 1911 Fox SW using 12 to 20 ga. Chambermates. (Even run a few 100 straights on skeet targets with 'em.)

The key is to forget about using the grease they recommend, and instead wrap over the O-rings with 3-4 laps of the yellow gas pipe thread tape. This makes for a very tight press fit, but the tape will last for 200-300 firings with no blowby and usually the O-rings will survive for reuse.

No problem ejecting factory shells or reloads either.

Mark

A sailor's creed - "If you can't tie good knots, tie lots of 'em."