Planning stages for my combustion coaxial.

[Tango71]

Well gentlemen, in reference to my previous post: http://www.spudfiles.com/spud-cannon-re ... 25937.html
I have decided that a combustion cannon is the way to go. The only issue now is the type of ammo I will use. Golf balls are out of the question because they're way too big for the type of coaxial that I'm trying to build. The idea is to make it look like an authentic army tank cannon so the exterior barrel cannot be a thick 3" pipe. So far I'm thinking resin cast projectiles. These would be easy enough to make by mixing polyester resin with other materials (yet to be determined) in a mould and have realistic projectiles.

As for the cannon it will have between a 5/8" to 3/4" barrel made from seamless DOM tubing. The smaller I can get away with the more ammo I'll get per volume of resin. The outside barrel will taper outwards in to a small 3" combustion chamber with a breech lock type end cap. The breech lock will be made using some heavy duty 200 brinell piping used in the oil and gas sector.

I still have to run the numbers through the calculator and make official sketchup drawings and post them up once I'm done work in a few days but so far these are the plans.

[Bernie_McGee]

Have you considered marbles? They may be a little cheaper than resin projectiles. I have found that 3/4" marbles are a little loose in 3/4" SCH 40, but you could wrap a piece of tissue around them. They can be bought in bulk. You can also find 3/4" steel shot, although its not nearly as cheap.