What is the diameter of the barrel where it goes into the trunnion? Want to know to make a tool out of round stock for reverse riveting the trunnion by using a hammer instead of an expensive tool. And yes some folks have done it this way including a gun smith who wrote an article about it.
Let me add I know that the measurement is not absolute I just want a figure close to see what round stock I can get and then we will lathe it down to a friction fit. So basically I want the make a mandrel to fit where the barrel goes with a few improvements.
Also forgot the add my friend has the rivet tools/punch that you can form the round heads so appearance is not an issue.