Oh, hm.
Perhaps all of this holiday turkey and stuffing's working my long term memory a little too hard...
Good then, let's see what we can do to get your rifle going.
The cases you see above are short, like what you need for your rifle. That rifle likes two and a half drams of FFg Goex black powder, I have a fresh can of Swiss 1-1/2Fg that I'll be trying soon too.
I turned the cases from brass barstock to match my chamber casts, then hand fitted them to my chambers for a very snug fit.
I didn't run the walls as thick as a wax paper case, and neck them down very slightly to make up the difference. I wanted my cases to have a little bit of spring to them so as to provide a gas seal.
Over the powder, I run a little cup that I make out of milk carton material. I made a special punch and die to form them in. They resemble little paper water cups with very short walls.
I tamp the powder down with one of these, the cup facing the powder. Over that I set a 1/4" thick saddle felt donut wad that I soak with black powder lube -- essentially a paste that makes sure that the powder fouling remains soft from shot to shot.
I can easily fire a string of ten pairs of shots without having to clean or swab the barrels. The lube also renders the fouling relatively inert.
My firing pins are made of bronze alloy brazing rod material, and I use regular percussion caps for ignition. Black powder is easy to light, ignition's been very consistent.
If your gun is a twelve bore, the .690 balls are likely too small.
You'll want to run pure lead balls of groove diameter. Slugging the bores you might find that the barrels don't have the same diameters. Don't be suprised if that happens...
A tip on cerrosafe casting barrels--
Get two big soup pots of water boiling. Set the chamber ends of the barrels in one pot. That'll get them up to a temperature where the casting alloy won't flash freeze on the barrel metal.
Set up a double boiler in the other pot, I use a pyrex measuring cup to melt the alloy in. The handle and spout of the mesuring cup makes pouring the cerrosafe easy.
Plug the bores with cloth or paper napkins three quarters of an inch into the bores. That's enough to hold the cerrosafe back. Pour the cerrosafe into the chambers and short bit of the bores until it juuuuuust wells at the breech end of the barrels. Let stand to cool for about ten or fifteen minutes.
Then tap the casts out with a wooden dowel or cleaning rod.
Let them sit to cool for an hour and measure them.
You'll have chamber, bore, and groove dimensions of each barrel on each casting.
From there you can calculate what the wall thickness needs to be for your cases, and what your projectile diameter needs to be.
Hope that makes sense.
When I get a good repeatable method of modifying modern centerfire cases for pinfire use I'll explain it. At this point It's pretty much one-off modifications and experimentation.
And Gramps, post some images of that thing again. If I've seen them before, I've forgotten. I want to see it again!
--Tinker
