Good evening. Newish member here and new to sxs shotguns so please go easy on me. I recently bought a Stevens 311a (what I thought was a 12g) receiver on GunBroker per the listing. Found some 12g barrels for cheap and got them put on only to find out they stick out about 1/16th of an inch on either side. I am wondering if this is because it is a 16g+ frame? Or is this sort of tolerance normal? Is there any place to find out what the receiver dimensions are for a 12gauge from say 'ear to ear'? They snap right in and open and close perfectly. If this is the issue I now have a pair of 12g barrels in very nice shape I'll be looking to swap for 16g. Thanks for reading.