I screwed the plug in all the way (came with two breech plug tools) and you guys are correct, it fired with nae problem. Hefty firing pin fills that gap, strange design though... seems like a lot of wasted spark/flash escapes through that slotted nipple; in any event, thanks for your help guys, I will try and fire a few rounds next weekend. The rifle came with two cases of pyrodex pellets, 20 powerbelt 295gr bullets, possible bag full of all sorts of stuff, cleaning kit, enough bore butter to choke a donkey, BP cleaning solutions, patches etc... all for $80, I know the rifles are cheap but with all that gear I thought , what the hay! Thanks again guys.
Any man who packs a big bore Sharps carbine could come in mighty handy, if we're attacked by buffalo... or elephants. - Rooster Cogburn