One test was done on a rotary bolted L C Smith which had the chambers opened to take 3" shells. Testing began with full power loads & went up from there. Testing halted prior to a burst when the gun began consistently opening itself. This would be a result of the barrels & breech being Sprung Apart. I believe it would truly be irrational to think this was the result of the barrels being shoved forward, rather than the breech being pushed backwards.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra