Maybe I am missing something, but why do you think a jam nut would back off easier than a crush washer?
I was just saying from a physical standpoint.
A crush washer is metallurgically sprung against the muzzle device like a lock washer. A jam nut has no flex, its simply torqued like a lug nut. With minimal rotation its completely loose. Ive had jam nuts come loose on lathes, drill presses etc...