Although there once was a high-velocity commercial load using the 300-grain bullet back around 1900, and there is a new such load now, the .45/70's usually have a rifling twist better suited to heavier bullets. Here I mean ones of at least 350-grains, and better yet, 400 grains or more -up to perhaps 500 grains.

None of the .45/70's I've owned would shoot ANY 300-grain bullet worth two hoots. BUT, I have had good results with the Lyman-Gould 457122HP, a plain-base, hollowpoint cast bullet that comes from my mould, made of wheel weights,at 342 grains. For heavy loads, I heat-treat them to 18Brinnel hardness, and put an inverted gascheck on top of the powder charge before seating the bullet. I use 55 grains of IMR 3031 with this bullet for a MV around 1900 FPS.

In addition, I like the BarnesOriginal400-grain semi-spitzer which has a nice big hunk of exposed lead, and it has a real high ballistic coefficient-.389. Unfortunately, it is sort of pointed, so it would be a two-shot proposition in the Marlin-one inthe tubular magazine, one in the chamber. But this Barnes bullet definitely takes the .45/70 OUT of the short-range only class!

Those350-grain Speer and 400 grain Speer flatnosed bulletsare both good, but the 400-grainermay be a little too soft for BIG bears (OK on blackies, however). Loaded up, the Speer 350-grain is real potent medicine for big, mean/tough critters. (I wish Nosler made a 350 or 400-grain Partition for the .45/70.)

Use around 52-54 grains of IMR 3031 with400-405 grain jacketed bullets. Use 55-58 grains of the same stuff with the 350's.

In ALL cases, work UP from at least 5% below!