Answer to why not use a 45 colt conversion cylinder. --- The hammer is made to pop muzzloader caps only, and there is no breech block to hold recoil from cartridges. In short they are just made entierely different.
When making the BB to fit cap and ball revolvers I cut two drive bands, to slip fit the cylinder without pressure, then a drive band where the drive band on a round ball would hit, which is a couple thousandths larger than the cylinder. They go in dead straight due to the two slip fit bands, and the front band, being a press fit, holds them in place against recoil. For cap and ball they should be cast of pure lead if the cylinder throat will not allow bullet bases a bit larger than the barrels groove diameter. This so the base can slug up and get a good grip going through the gun. With the single Ruger which I developed these BB's for, bact about 30 years ago, a 44 by the way. throats were large enough so the base could fill the barrel grooves, so I played some with harder bullets, at around 20 bhn. They shot very well with a pinch of 4F over the primer cap, then topped off with unique to get slight compression. About 1200 fps. I wouldn't do that with any other cap and ball revolver that I've seen. other than the Ruger.
I have made quite a few for cartridge guns, both rifle and handguns, and when making them, I cut two drive bands large enough that they can be sized to desired diameter, and a grease groove that is filled same as with any cast bullet. I could cut for gas checks too if one desired but because of their light weight they can endure screaming speeds dressed with a plainbase. One customer shot them into an inch at 25 yards with a velocity of 1800 fps out of his ruger 44 blackhowk. But that guy was as much experimenter nut as I am, and most people see no sence in going there with a tiny weight bullet. They are really at their best when velocity is lower like 1200 fps and lower down to 600 fps if one wanted to shoot that slow, to keep the noise down. They stabilize almost as easily as a round ball, which being interpreted means a very slow rifling twist will keep them stable. For cartridge guns, one can use very soft lead for low velocity use or hard lead, which will tend to be more accurate and definately stand more speed without leading. The gun I used was borrowed from a neighbor friend, who got the mold for letting me play with his toy. He killed a black bear with it, by the way.
I make most with a subtantial falt, if the customer what's them for game and pest shooting, but making the complete ball is no problem. Just a customer choice. But when making the choice, keep in mind that a 38 or larger round ball moving at maybe 700 fps, really puts the hurts on small pests, FAST. So the flat really isn't needed for most shooters. I don't recall cutting one smaller than 30 caliber, and the most recent one was something over 50 cal, maybe .60, but i don't recall that exactly.
I wil make them in any diameter asked for, so cannot hope to give a weight, except that they are quite a bit heavier than a round ball. Perhaps 20% heavier, but thats a guess.
