Welcome,
TomCatPC.
I have one of those Lyman Plains Pistols in .50 caliber. It is capable of very good accuracy if the shooter does his part.
Zonie made some excellent suggestions with regard to starting loads. The Lyman owner's manual says the
maximum recommended load for this pistol is 40 grains of FFFG under a .495" ball. That is on page 14 of the
Lyman User's Guide, available free online. Just click the link. Oddly enough, I didn't find a recommended starting range for the powder charge in the manual, but
Zonie's suggestion sounds good to me. I haven't settled on a load for mine, but was experimenting with 35 grains of FFFg. I (and some others) have found the .490 ball is hard to load. I have gotten some balls in .480", which is probably not tight enough for best accuracy, and in .487", which might shoot well and be a little easier to ram, but I haven't tried either of those in this pistol.
I would recommend that you get a copy of
Percussion Pistols and Revolvers, by Johnny Bates and Mike Cumpston. Amazon has it. This book has a whole chapter on the Lyman Plains Pistol. The authors experimented with various propellants, including both Goex and Swiss black powder and three different BP substitutes, with charges ranging from 20 grains to 40 grains, with patched round balls, Lee R.E.A.L. bullets and Hornady 385 grain Great Plains Bullets. This is a very sturdy pistol, tolerant of a variety of loads.
Regarding historical accuracy, it is "similar" to a number of late fur-trade era pistols, but it is not an attempt to copy anything in particular, as far as I know. The "snail," or bolster, where the nipple screws in, is unlike anything you are likely to find on an original. Here is a Tryon pistol from the early 19th century, for comparison:
This next one is a pistol by A.W. Spies. The hammer spur was unfortunately broken off at some point:
The Tryon pistol is half-stocked, like your Lyman Plains Pistol, but it has a back-action lock and a captured ramrod. The Spies pistol was converted to percussion from flintlock. It has a full stock and a brass barrel, unlike your Plains Pistol's half stock and steel barrel. You see a lot of variation in the pistols of that period, and I think the Lyman is a composite of features from a variety of sources. In my opinion, it was probably
inspired by the "Factor's Pistols" which were offered by the now-defunct Green River Forge and the "Trapper's Pistol" from the also defunct Green River Rifle Works in the seventies and eighties. The first was a fullstocked flintlock, but the GRRW Trapper's Pistol was available in percussion or flintlock, halfstock or fullstock. North Star West also made a simple Trade Pistol in flintlock, similar in style to the Green River Forge pistol. This was available until NSW closed up shop just a few years ago. You rarely see any of these three pistols up for sale on the used gun market. People who own them tend to keep them!
If you are interested in original single-shot pistols of the fur trade, the American Society of Arms Collectors published a great monograph by Charles Hanson in the
ASAC Bulletin 62:9-18. You can access it right here:
Fur Trader's Pistols
I think the Lyman Plains Pistol, like their Great Plains Rifle, has some nice features but some room for improvement. It would be great if they would offer an upgraded version, as they have done with the "Signature Series" Great Plains Rifles. The Plains Pistol could definitely use a more authentic and more ergonomic grip shape, better sights, and a nicer-looking snail. Ain't gonna happen, though.
Regardless, the Plains Pistol is a good shooter and a good value. I hope you enjoy it!
Notchy Bob