The file 'Shotgun Plug Aka Duck Plug 3D Printer Model' is (fcstd,stl,scad) file type, size is 30.9KB.
My 12 gauge Stevens Model 77h shotgun was missing the plug. In Pennsylvania if I want to use the gun for small game it needs the plug to limit the total number of shells the gun can carry to three.
Admittedly you can use something like a wooden dowel to do the same job. This was nice because I did not have to hunt one up and 3D printed stuff is just fun.
In searching online this plug is often called a "duck plug" apparently the federal government requires it for duck hunting as well.
As I said I made this for my Stevens shotgun, but I'm thinking it may work for others. In my gun this seems to work well and doesn't make any rattling sounds.
Update 11/22/23
Added customizable plug made with OpenSCAD so people can make the exact size and number of fins that they want. See how I made it here:
shotgun_plug.fcstd | 20.7KB | |
shotgun_plug.stl | 40.1KB | |
shotgun_plug_remake.scad | 548.0B |