it is possible to shoot 3"from a 2 3/4 receiver. My dipstick cousin used to shoot 3" slugs from his 2 3/4 express (12 ga), only problem he had the hullwould not eject every time, too long for the opening. he didnt seem to think much of it, told him the next time he pulled the trigger may be his last. He finally discontinued such practices and stepped up to a SBE, dont have to worry about him anymore.

***** very dangerous, i would not try this*****