This sort of problem is quite frequent with the tm tommy guns... As soon as the two screws that hold the barrel in place loosen the damn thing craks quite easely. Locktite (blue) is your friend on the two lower and the top setscrew
This is my fix on the issue
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Vondnik, team Bad Karma, PQAC
Murphy's second rule: Nothing is impossible for the man who does not have to do it himself.
