in the first thread, what started out as 45-70 sleeved/fireformed to 43 Beaumont, morphed into 8mm Lebel fireformed to 43 Beaumont...along with 43 Spanish and other vintage 11mm shells being cut off/fireformed as well. it wasn't planned that way, just sort of happened as I ran into some very cheap vintage 8mm Lebel ammo, and started cleaning out my old shell collection to do test fires with it.
truth be told, the most promising of them all was the 8mm Lebel case to 43 Beaumont, it fireformed nearly perfect on the first shot, just being a bit short on case length- and it didn't have to be sleeved like the 45-70, eliminating the need to buy brass tubing, cut it to size, and put it over the case. the downside was, the Lebel case was milsurp and Berdan primed, the primers were bad, and had to be drilled/converted to shotgun primers to fireform.
I'm starting this 2nd thread because the original thread doesn't mention 8mm Lebel in the title, and it's very relevant. If I was going to start off again from a clean slate, it would be with boxer primed 8mm Lebel brass, loaded with 16gr Trail Boss powder, and fireformed in the 43 Beaumont rifle with 8mm bullets. No sleeving. It would be the quickest, easiest way to make 43 Beaumont brass IMHO, and requires no dies. Lebel brass is 76 cents each at Midway USA, status "backorder ok" meaning they will get more.
the 348 Winchester cartridge would probably do equally well- but the 348 being so far upscale from the 43 Beaumont, the brass is generally much more valuable to someone with a M71 lever gun, than a Dutch Beaumont rifle.
looking over some other rimmed cases that may fireform easily to 43 Beaumont, the 30-40 Krag came to mind. downside, it's longer and would have to be trimmed quite a bit. I've had a few Krag rifles, and still have one sporter Krag w/open sights, along with some loaded ammo, brass, and dies in 30-40.
In this thread I'm going to fireform both the sleeved 45-70 and 8mm Lebel brass a 2nd time with no tape, to get it to fully fireform to the chamber, and finish those tests. then fire the one old unmarked case, and other Lebel case- both of which didn't fire the first time, due to bad primers.
Later, my goal is to load up 1 round each of 348 Winchester and 30-40 Krag brass in a similar fashion, i.e. 16gr Trail Boss and the original 348 and 30 cal. bullets, and fireform them in the Beaumont rifle. While the 30-40 Krag brass isn't quite as upscale as 348 Winchester brass, it still falls in the category of "it should really be saved for a Krag chambered rifle", and not ruined to use in a Beaumont. But it won't hurt to try one round of each to see what happens in the Beaumont.
again, I don't hold this rifle to my shoulder and look down the barrel on any fireform experiments like this. I value my eyes and face and life, way more than that. They'll be fired with a 50 foot long string, with the rifle tied to the bench. Once the brass truly fireforms to the chamber to provide a reliable gas seal, only then will the rifle be shouldered when that brass is used again. I also learned, that any old brass from turn of century or older time period, should not ever be fired from the shoulder. The antique brass is brittle, and even when used in the correct sized chamber, may split and spew gas back towards the shooters' face. So far every single old brass case from late 1800's-early 1900's has split badly, even after being annealed first. There is only one of those cases left, one that didn't fire due to bad primer, and had no case head stamp- that one will also be fired today.