I took the Erma Gallagher out to the range today. Managed to get 16 shots off at 50 yards, no mean achievement. The only .54 caliber mould I have is for the linen cartridge Sharps rifle, but it seems to work OK in this carbine. It can't be seated in the Gallagher cartridge case, so I drop the boolit into the chamber and seat the case full of powder afterwards.
There are two types of cases available from S&S Firearms, the "thick" and the "thin." The "thick" cases only hold about 50 gr of powder maximum and the vertical scatter is pretty bad. The "thin" cases can easily hold 70-80 gr of powder, and around 70 one begins to see small clusters like the "core" group in the picture. The holes around it are the lighter powder charges. I blowtubed throughout the session. Some people have given up on their Erma Gallaghers and relined the barrels to .50 caliber, but my example is beautifully rifled (multigrooved like a cannon barrel) and seems to be plenty accurate to me.
The reason the 16 shots was noteworthy is that these high-capacity cases with the heavier loadings have generally given me no more than 3 shots before I get one stuck in the breech section of the chamber, and then shooting ceases for the day. This time, by dint of applying Frog Lube with a Q-tip to both the breech section of the chamber and the part of the cartridge case that sticks out of the barrel, I only needed to use my extraction tool (made from a Taiwanese wire stripper) a few times, and each time it actually worked.
You can see there is not a lot of room to get a case out of the breech even when the barrel is tipped forward. This design was vastly unpopular with the troops in the Civil War, and at least back then it was no big deal to wreck a fired case by mangling it out of the gun with pliers or whatever. The current cases are pretty expensive for that kind of treatment. I think I'll try to make up a ring die and plunger so I can size the cases back to where they won't have the potential to stick so badly. But as an expedient, the Frog Lube worked very well.
My Gallagher has primitive sights and a fierce trigger pull, but it is one of the few Civil War carbines stout enough to fire charges beyond the power level of pistols. It impressed the guys firing their ARs at the nearby benches.