Hi Mike, I had the samething happen to me with one of my hammerguns. Mine was the result of headspace and the pin being to long. Mine also locked uo tight.

I sent mine (the whole gun) into Keith Kearcher and he fixed it in record time.

If the primer is being pierced with only the WR shells and not another brand, then of course, it's the WR shells.

Just to be on the safe side, I'd just have it checked out and have whoever does the work test fire it for you with the WR shells.

Good Luck!

Greg

Gregory J. Westberg
MSG, USA
Ret