Hw30s. Many issues. UPDATE, every pellet is key holing.

[stevemag]

i had my x20 detonate when new, blew the breech open .
id bet that detonation of yours damaged the seal at least. id sent it back (if you can).
as for the key holeing, I'm in with everyone else, seems unlikely . if you keep it, try a wooden board or another stiff target, than open her up and check for damaged seal.
still would send it back if you can.

[Methuselah]

The 'shoot the bottom of a can' suggestion was offered as an alternate method to check for key holing.

All that detonation is something else entirely. Never hearda one that blew the breech open.

I never would have thought of the can suggestion on my own  .  Very nice

My breach on the D34 popped open 3 or 4 times over maybe 30 shots and I believed it to be caused by the detent ball bouncing from piston slamming (had a bad breach seal).  No proof, but could not come up with a better fitting reason - doesn't seem to fit what is going on in Logan's case though.