Liner for small brass cannon

[racer123]

Hello,
I have a small brass cannon I would like to make safe to fire.
The barrel is 3/8" ID and 1" OD.
As it is brass I am not sure I trust it to be fired as is.
I would like to make a steel powder chamber and weld on a piece of seamless tube as a barrel liner.
I understand the rules for the powder chamber design of wall thickness equal to bore diameter all around.
How do I work out what wall thickness I need to use for the liner tube?
I am currently looking at using 3/16" bore with OD of 9/16" for the chamber and 1/16" wall seamless hydraulic tube for the liner leaving a bore of 7/16".
Also are there any rules as to the depth of the powder chamber?
I was going to use 1/2" but reading the handgonne threads they seem to use a lot deeper chamber like 1" to 2".
Thanks for any help.
Regards
David

[Double D]

3/8 in bore, huh.  That is .375.  Measure and be sure.  I would not line your barrel.  I would instead  ream your barrel to .395,  and use ball and patch.

You cannon is small enough to not really need the liner.

[GGaskill]

As long as you don't use excessive powder charges, you should be OK unmodified.

[racer123]

Thanks for the advice.
I had heard that brass was not safe as it risked stress cracks.
So if I use it as is how do I decide how much powder to use?
Plan is to fire lead sinkers.
I have FFFg and Fg powder available.
Regards
David

[GGaskill]

Plan is to fire lead sinkers.

Split shot?  Something you cast yourself?  You should check out Lee Round Ball Moulds.  .360" would be good for a .375" bore.

[Double D]

Look for laod information for a .36 calliber revolver and reduce the load and work up,

[racer123]

Looks like 20 - 40 grains of FFFg is the load for a .36 cal revolver.
So I will start at 10 and work up.
Thanks

[Double D]

Don't be surprised if you first shot or two just kind of squirts out an then all of a sudden  at the next increment the balls takes off.

I would also use FFg in the brass gun, it has a slower burn rate less pressure.

There is also one other very important item, when you shot the gun take pictures video if you can, we absolutely love smoke and fire on this board!

[gulfcoastblackpowder]

I agree with the others' recommendations.  At that bore size, it will behave like a pistol barrel, in which some brasses have been successfully used for centuries unlined.  You can load it like one, with cast round ball (you can buy precast balls or cast them yourself).

x2 on the pics!