I have been trying to work up a decent load for my 1873 (1884?) Springfield Trapdoor Carbine. Original barrel cut to 22" and restocked into a Montecarlo Rollover (Hideous, I assure nyou, but purchased it pre-butchered). I have had middling luck with it and feel like it will shoot better than 6" at 50 yds. Have used the Hornady .458 Cal 350 gr. S.P., Lee 320 gr RNFP, and an old Lyman 500 gr RNFP. Have been using 1/4 part Linotype to 3/4 parts pure lead with 50/50 Alox/beeswax lube. This does not lead the barrel, but I think this is where my accuracy problem lies. The barrel is mirror bright, lands and grooves are sharp. Slugs to .458", and have sized bullets to .459, and .460. There seems to be nothing mechanical causing inaccuracy.
I cast a quantity of 500 gr bullets of 20 to 1 lead to tin alloy today and will be using iMR 4198 and RX-7 to work up loads. My thoughts are that the harder bullet is not "bumping up" or that with a harder alloy I am getting gas blowby. Anyone have any thoughts on this or a powder reccomendation that would work. I have scanned all of my literature and checked my powder supply and this is what I have. Any assistance would be greatly appreciated. I'm going to scan the site to see if anything is extant per my troubles.