Great choice there, Jerry. I"ve been shooting the NEF 45/70 for 13 yrs(and 22 deer so far) now and in mine it likes IMR 4198 for the 300 grain bullets of any variety. What load you adopt will of course depend on your shooting conditions/game, I reckon. The top load I could use comfortably(not the top load I tried) was 51.2 grs of IMR4198/300 gr JHP of any variety/ Winchester cases/Rem 9 1/2 primers for 2173 fps. It's the high end Marlin load in my Hornady Manual. Developed 28 ftlb of recoil at 15 fps and over 3000 ftlb of energy. Actually for my woods hunting for these big PA whitetails in the close woods I hunt in, I ended up dropping down to 42.5 grs of 4198 for around 1840 fps. Comfortable load to shoot and killed them deer just as dead without the bloodshot meat I was getting from the higher velocity loads. This year I"m using the Speer 400 gr FP behind 44 Gr of Reloader 7 for what a friend of mine who shoots the load in his NEF says cronographs at 1750 fps. Kicks like a mule from the bench, but not bad from "hunting" positions. That soft bullet is supposed to work really well on deer, from what I hear. By the way, I neck size my brass, and don't crimp. All the 300 grain loads I tried grouped into an inch or less at 100, as does the 400 gr. The ol' 45 is just a naturally accurate cartridge.
