I just acquired an G20SF from a forum member. Bought a Lone Wolf threaded barrel for it. Put it in and loaded the mags with Underwood 165gr GD's. inserted the mag and pulled the slide back to chamber a round. Let slide go at the pulled back apex to allow it to return to battery, didn't' ride the slide forward at all. Not one round fed properly. Every round caught on entering the tighter chamber. Eventually was able to properly chamber a round by tapping the mag into a higher seating. This only helped occasionally though. Tried the other mag and had the same FTF. Have some new mags on the way, but I believe this is an issue with the barrel. Does anybody agree with me? Or could be bad mags. Looking for some help folks. Thanks in advance. Shoot straight and stay safe.