Hi, Gary and folks,
A shade OT, but just from curiosity, I wonder if you have ever seen the Sharps pellet primer work. Not many have, with a tube of primers now selling for over $100, but once upon a time they were less expensive, and I fired a Sharps using them and linen cartridges. The primer pellet is priming compound enclosed in thin copper, sort of like a miniature cap box. The little tongue is operated by a cam cut into the inside of the hammer. When the hammer falls, the tongue kicks out the pellet just in time for the hammer to flatten it on the nipple. Some writers have said that it is like a percussion cap or that it is "laid on" the nipple. Neither is true. The pellet is flying through the air when the hammer comes down on it. It is a neat bit of timing and seems to sort of work "on a prayer", but actually it is pretty reliable.
Of course, the gun can use standard musket caps as well, a good idea in case a soldier ran out of Sharps primers.
Also very few old Sharps rifles or carbines will slice off the end of the cartridge like they should, the breech block insert having been worn down or rusted. But with the breech and breech block in good shape, the end of a linen cartridge comes right off, exposing the powder.
Jim