So, I recently came across an 1879 takedown for sale and the price was good so I picked it up. I checked the gun over and picked up some light target load to test the gun out.

Except I couldn’t. I slammed the pump home only to find that the shell wouldn’t go into the chamber. Pulled the slide back and it ejected. Tried another. No luck. 

After further inspection and taking the barrel assembly off the reciever, I realized that even tho the barrel is stamped 12 gauge, the reciever is stamped 16. Someone changed out all the internals so it would accept 12 gauge shells, made a new barrel block so the 12 gauge barrel would fit on the reciever, but left the 16 gauge barrel chamber/headspace ring in. 

If you’re confused, welcome to my world. Any advice is helpful.