JW...

I believe that's called a "falling block" and is pretty much what the rifles developed by Christian Sharps were. They were used by famous outfits such as "Berdan's Sharphooters" during the Civil War. They did not use a metallic cartridge, they instead utilized a paper cartridge which contained the charge and the projectile. When the action was opened, a paper cartridge was inserted into the breech and the action was then closed. This sheared the tail off the cartridge exposing the charge which was then ignited by the percussion cap. They were breechloading single shot rifles that were known for their accuracy and reliability as well as the speed with which they could be reloaded during a fight. After the war they were re-designed to accommodate metallic cartridges and the percussion nipple was replaced by a firing pin mechanism.

If you dig around on the net you'll probably find info on how to make your own paper cartridges. I would check with the NSSA, those folks are into everything Civil War era with regard to that period's firearms and their use.

I believe I have a box of .54 conicals that were meant for that type of weapon somewhere around that I bought by accident years ago and then discovered my mistake. I'll PM you if I find them in case you're interested, they're of no use to me.

BPS