With all the references to these H&R single-shot 12's, i'm remembering the one i have.

Admittedly, i've only shot 2 3/4" out of it.

That little bugger seemed just a bit light to be shooting 3" loads even though it's chambered for 'em. The 2 3/4" seemed to give plenty of "feedback".

3" loads in that thing?!!? No thanks!!!