Hi, looking for some ideas as to whats happening. Winchester white box 240 gr. LSP is jamming up my Mod 29 with high primers. The primer is sunk a bit in its pocket but bulges after fired. This is one of those guns I've had but never shot and the ammo is a couple of yrs old. So, my questions are, is the gun or the ammo at fault and what should I do about it? I'll try new ammo next chance I get.