I've got a Pedersoli 1859 Sharps (percussion) that I have been struggling to get to perform well since 2016.
I have come to believe that with an of the "Christmas tree" type of bullets, with 3 progressively larger driving bands, that the first driving band should fit in the bore. That is, if you stick the bullet in your muzzle pointy-end-first, the bullet should stop on the second driving band, with the first band going down the bore.
With my Pedersoli 1859, no commercially available Christmas tree bullet I have tried does this. Not even the Pedersoli mold. I have tried several variations of Christmas Tree bullet, including a Rapine copy (made by Lee as a custom mold someone sold on ebay), The Pedersoli version, and a "Bobtail" custom bullet. With all of them, the front driving band is too large to fit into the bore of my Pedersoli Sharps.
Why does this matter?
As I was slow to understand, the guys that shoot cartridge Sharps guns use bullets, either "naked" or paper-patched, that slide into the bore when the cartridge is chambered. Some of these bullets are only barely held by the case mouth by perhaps 1/8" of bullet or so. The remainder - a couple of inches or so - slides into the bore like a torpedo going into a torpedo tube in a submarine. These bullets do not engage the rifling on firing like a usual modern firearm. They are not a couple of thousands over
groove diameter like with most modern firearms. They slide into the
bore. What I believe this does is provide very close coaxiality between the bullet and the bore. Upon firing, these long bullets collapse along their length, which makes them swell up in diameter and thus take up the rifling.
I believe the Christmas Tree Sharps bullets were intended to do the same thing. I have been loaned several original Sharps bullets of different designs (some are Christmas tree, some are standard "ogive" bullets that have a curious small and around the ogive which, now not surprisingly, fits the bore). With all of them but one, the front driving band fits in the bore. I believe the one that does not would if I forced it, but I do not wan to damage the patina on the bullet.
When I was doing load workups for my
Smith carbine, I tested the usual hard black plastic tubes and the translucent soft red rubber tubes made by Yore (
Yore Supply - Rubber Smith Tubes). I really liked the Yore tubes for two reasons. First, being flexible, it was easy to get the bullets into the case mouths. Second, being translucent it was easy to see if there was powder in the tube and how close to full you were when the bullet was inserted.
Unfortunately, during load workups using both the hard black plastic and the Yore tubes, I discovered that I got better accuracy with the hard black tubes. I believe that this again is due to coaxiality. With the red rubber tubes, it was trivial to end up with bullets that were "cock-eyed" in the case mouth. You had to deliberately eyeball them to set them straight in the tube. And of course any kind of handling while plucking them out of your cartridge box and/or loading could knock the bullet crooked. But with the hard black plastic tubes, the bullets are
very tightly and rigidly held by the case, enforcing coaxiality with the case. Since the cases tend to fit tightly in the Smith chamber, I believe this results in good bullet-to-bore coaxiality and this accounts for the increased precision on target with the black tubes vs. the red ones.
I now believe this can be applied to the Sharps also. It has been a maddening journey, because I have done many load workups over the years with this gun with different bullets, and often come home from the exercise excited because I finally found "the best load" for a bullet. Only to find later that it must have been a fluke because I was no longer getting consistent results.
I now think that part of the problem is lack of consistent coaxiality on loading with non-bore-riding bullets. The paper cartridge of combustible Sharps cartridges must be necessarily smaller than the chamber or you won't get many shots off before the cartridge won't fit and you will crumble it if you try and force it. What this means is that when you push a non-bore-riding bullet/cartridge into the Sharps chamber, the tail end of the cartridge will naturally settle to the floor of the chamber due to gravity. This may tend to cock the bullet skywards slightly, making it non-concentric with the bore. Depending on how dirty your chamber is, how much lube is on your bullet, and how firmly you push it into the chamber on loading, you could get different degrees of coaxial alignment each time you shoot a non-bore-riding bullet.
By having a bullet that at least partially bore-rides, I think this helps get the bullet concentric in the bore. It's never going to be as sure a thing as with the
cartridge Sharps guns, where you have an inch or more of bullet surface riding in the bore, but I think it helps.
Larry Flees (who does fantastic work on Sharps guns, eliminating their gas leak problems at the breech), has designed a Christmas tree bullet that has a front driving band that will bore ride in the Pedersoli Sharps. While I have not had time to extensively test it, my initial load workup has provided some of the tightest sub-one-inch groups at 50 yards off a bench I have ever gotten. Targets here:
Both 42 grains of 3F Goex and 48 grains of same gave <1" groups at 50 yards off a bench.
The Flees bullet has a heel designed to accept the Charlie Hahn cardboard tubes. These have the advantage of shattering/disintegrating very completely upon firing but also are quite rigid, which makes for a very rigid and consistent complete cartridge. Many times on inserting and pushing home a home-made rolled-paper cartridge I can feel the tube buckle/crinkle when pushed home into the chamber. I'm sure this results in random and strange bore alignment for the bullet, especially if not a bore-rider. But the Hahn tubes are very rigid and so never do this. I think they also contribute to a more consistent chambering of the bullet and cartridge.
I haven't had the time to use this new bullet and cartridge in competition to confirm that it is the "magic bullet", but I think it is. I think having a bore-riding bullet is a way to get great accuracy out of a Sharps.
Steve
We've all been there, and it's a nice hunk of iron (even better in that regard than The Rock!) to haul around.
… I’ve been looking at it for quite a while & I know it’s probably overkill for me but I bought a chrono and a number of things I don’t really use or at least not that much. 
