Tell me what a weak fireing pin is please, Ive been a gunsmith for some time now, I would like to know for the future so I can diagnose weak fireing pins. " Yes Im being a SMART-BUT"!!!. A broken fireing pin, a worn fireing pinor a corroded fireing pin could be the culprit, but it is just the device to relay themass of the hammer made by the mainspring to the primer of the shell. So it might have a weak mainspring also, and yes it can have chamber issues, if the pivot pin is worn enough it could have excesive breach space, thus when fired the fireing pin could run out of forward momentum causing a light strike due to the shell being too far away. My sugjestion would be to take it to your local gunsmith and have it checked out and remember these are a cheap shotgun, due to cost it might not be worth fixing if it is excesive breach, fireing pin or spring issues wont be all that bad.