one of the older versions of the Savage O/U, the kind where the barrels were soldered together. I seem to remember that they were thick enough for such. Need at LEAST a 1/2" OD barrel, tho, or the threaded joint will be much too weak for a shtf rifle. Rifle muzzles have a bad tendency to get knocked on things. So the 5/16" x40 TPI thread is a poor idea. That WILL suffice to mount a can on a 3/8" OD barrel. I've used such a method to mount cans on dozens of Jennings .22's.
Why would someone want a suppresed O/U combo gun?and who plays with jennings?, they are a POS of the first order. If these are examples of the work you produce please post a picture so I never buy anything from you by mistake!
gun and can, stupid. So if I used a $200 gun,instead of a $50 gun, that was just throwing away $150, times the 40 Jenning's that I silenced. Now maybe a dumbass like you would do such a thing, but I wouldn't.. I made and mounted those 40 cans in 4 days.
ALL noisy shots are a BAD idea, for shtf, or even for normal hunting. They scare off the OTHER game, attract unwanted attention. With a can and subsonic loads, a MISS often doesn't scare off the animal or bird that you shot at, dummy. THAT'S why you want a can on ANY hunting arm, dummy.
Thats amusing, where did You meet 40 people who would give You money to fix a can on a POS jennings, and how did You get 40 without tripping some flag in some database somewhere? I and the rest of the world would like a explanation please. Oh, Could You put .223 fan back up in the drivers seat for a while he's funnier. It must be a real bitch to have that many split personalitys.