Skip, I had the exact same problem with a recently built (2003 I think) Garbi model 101 sidelock; a pretty expensive gun, if Spanish (nothing wrong with most Spanish guns). Shortening the firing pins solved it. There is nothing wrong with your shells, new or reloads, or your chambers. If you can place fired shells in and remove them from the chambers easily, forget about the chambers. The problem is the firing pins; they are too long and need to have a hemispherical radius, not conical. I suggest you stop shooting the gun until you fix them or you will sooner or later break a firing pin. A fairly recent post discussed how far firing pins should protrude. Salopian suggested .055" but I think that may be too far. I measured 3 of my guns and all are in the .030"-.038" range. None have ever failed to fire a shell.
Joe
