Originally Posted by
Backwoods7
If it has a M in the serial number it's a magnum but the barrel should asso have for 23/4 or 3 in shells Marked on the lefthand side of the barrel in front of where it joins the action
+1 Any shotgun intended to use 3" shells will be marked "2 3/4 in. or 3 in." on the side of the barrel.