Maybe I'm missing something but no-one has suggested that the strikers are hanging up in the primers. This would make it horrible to open and would probably only need the strikers easing back a little.
It doesn't necessarily need to be jamming shut, just very stiff. Look for a smeared primer where the striker is rubbing as the gun begins to open.

Last edited by Toby Barclay; 05/10/12 03:45 PM.