Thanks, guys! I appreciate the input.
Since I can get the Gallagher at what I regard as a 'steal' (c/w 10 cases, wads, balls, mould for conicals) I think I'll take it for the challenge of making it shoot acceptably, at least to 50 yards.
Preacher - yep, 12.7mm equates to .50 calibre. Looks like ERMA may well have used MG barrels to make them. I didn't realize MA Deuce had such a fast ROT.
The current owner told me he shot it only with PRB. He didn't mention how he lubed them. I have on hand two .54 conical moulds; one Lee .54 Minie and one NEI 540 gr 'Xmas Tree' for my .54 Shiloh. Also a 550 RB mould, balls from which I could swadge to suit.
I've got a whack of Charlie Hahn's paper tubes, the kind that socket over the 'ringtail' of the Sharps 'Xmas Tree' bullets. I'm wondering if they would work in a Gallagher ....? There would be no gas seal as when using a brass case, but since there were paper and brass/foil original cases, quien sabe ...?
I only looked at one of the seller's brass cases and it was a reduced capacity case, a lip at the mouth where he placed a wad. Is that the norm? Doesn't look like much of a powder charge.
Ol' Gabe - the Gallgher barrel breaks, much like the Maynard and Sharps & Hankins, but it also drops down; a real turkey of a design! That's what appeals to me ... ;>)
Schiffer's book mentions that only the early Gallaghers had slow twist barrels. Later models used a faster ROT, and he had no example to test. I'm hoping that the ERMA's fast twist will stabilize a heavier conical, as it does in other BPCRs. If not, I may opt to get it relined to .50 and try the 350 gr Spencer bullet.