Here's some notes I saved from this site about DA chokes for my 12.5" pump.
Grizzly chokes
They accept a Mossberg Accu-Choke, Winchoke or Browining Invector. The remchoke works as well but may not bottom out.
Invector plus will not work.
Remchoke:
It's not the thread that's the major difference, it's the length of the un-threaded portion of the bottom of the choke. Winchoke/Invector has a longer unthreaded portion than RemChoke does. If you screw in a RemChoke it will "bottom out" on the threads without the bottom of the tube coming to the bottom of the choke tube recess in the barrel. About a 2mm gap, enough to start catching plastic, lead, etc.