The gun doesn't "open up", it just moves the key a bit upward, disengaging the interupter.

I have had several folks over the years call me to tell me it happened, and witnessed it one time when Remington 2 3/4" game loads (the black case rounds, I suspect they were pretty hot loads) were fed to a Charlin 12 (a beater, owned by a friend, during patterning testing-he knew he was abusing the gun, and didn't care).

The worst case was an otherwise fairly good mpls. area gunsmith who reported he saw it happen on a "Darne". I asked if was actually a Charlin he saw do that, to which he replied "same thing".

It does, and can happen, but, is NOT the guns fault.
Best,
Ted