I had a glock 17 with a guarder threaded barrel. It worked fine without a silencer on it but when I put a gemtech blackside (What I purchased intially) it wouldnt cycle properly. I'm thinking it was weight issues. I never did get to try it with a feather silencer, but im thinking that makes the difference. If I remember correctly, the blackside weighs 2 pounds or so.
Heres the threaded barrel I had:
http://www.airsoftgi.com/product_info.php?...roducts_id=2592