Different method of attaching trunions to 40mm bbls

[Frank46]

After reading Moose's53 post regarding his excellent work on the 40mm cannon I thought that maybe there was an alternative method of attaching the trunion ring to such a barrel. In Moose's posts he threaded the bbl over the breech area and applied a threadlocking compound. What about turning a straight section, threading it and the trunion ring with trunions attached and just for insurance adding a threaded locking ring in front of the trunions?. Granted any work on the breech end regarding the breechblock would have to be done after the trunion ring is installed. Frank

[Double D]

What pre 1899 cannon are you replicating to do that?

[moose53]

You would the need the major diameter of the barrel threaded section to be enough larger then barrel to allow the minor threaded section to clear the muzzle and forward taper of the cannon . Most barrels don't have a swell to work with where the trunnions should be . A counter sunk split ring could be threaded and the outer trunnion band could lock it on . Might be a viable way on bronze cannons that would be hard to weld on.

[GGaskill]

Actually, welding bronze is pretty easy with TIG if you use the right alloys.

[Frank46]

Douglas, was reading Moose 53's posts and if I got it right he welded the trunion ring to the sleeve he installed over the chamber. It was mentioned that this would eliminate the need for welding directly on to the 40mm bbl.
I was curious as to wether or not threading the bbl and trunion ring and using the aircraft sealant would work.
This was if I ever got lucky and got a piece of 40mm bbl for my own use. Or instead of using the sealant use permatex hardening pipe compound. And instead of using the rubber obturator use sheet copper at the very front and back of the breech block. Sort of like a flexatallic gasket used on steam lines. Frank

[Double D]

Okay...

[michaelfreeland]

This topic is very timely, as I'm getting ready to take my 40mm Bofors BBL off to the thread grind house. My plan is to have then grind and thread a 4 1/2" flat, then thread it to take a sleeve, which will have the trunnions themselves attached. Does this make sense ?

[moose53]

I am not seeing something here , how do you intend to thread the 40mm barrel for a trunnion band ?

[michaelfreeland]

On a thread grinder. The beauty of being in the Detroit area is that you can get ANYTHING turned/bored/ground/milled you want, and now cheaply. There's only one guy in the area that can hold a piece of this length between centers. They have the ability to I.D. grind as well