Most 16 ga M-12s do not reliably eject fired 2 3/4" domestic hulls. Empties that just slightly exceed 2 3/4" do not clear the port. And no, I am not referring only to sub-500k SN M-12s with 2 9/16" chambers.

RGLs are a best bet among domestics, with only an occasional excessively long hull. It goes downhill from there.

B&P 16s are stout, but among the very best performing field loads, IME. They do not hang up in M-12s.

Option of using 2.5" RST, Polywad, etc. remain.