That's a stout load, depending on which brand of 4198. H4198 seems much slower than IMR4198 in my experience. This will really smack something. I would be interested to know the velocity.

You really have to be aware of the differences in 4198.

In my A. Henry I loaded 72.5 IMR4198 (the old IMR before Hodgdon bought the company) behind a 560 grain paper patched lead bullet and got 1746 fps.

Then with newer IMR4198, made under Hodgdon's ownership, the same load yielded 1683 fps.

The same load, using H4198 yielded 1656 fps.

A load of 76.0 H4198 yielded 1783 fps. I switched to a F215 primer with the H4198 because it seemed to need more fire. I was getting erratic ignition.

I would postulate that a jacketed bullet will develop more pressure than a paper patched lead bullet.

For reference, the original black powder load was:

167 grains black powder, 560 grain bullet, 1740 fps, 10 tons pressure. This is your benchmark, and the load you want to duplicate.

Hope this helps.

The .577 2 3/4" BPE is a real ripper!!!!

Curl

P.S.

I failed to mention this. With each of the above loads I filled the excess space with three 24ga. 3/8" felt wads. It's absolutely necessary to use some type of filler to take up the air space.

Recently I bought a coil of 5/8" backer rod, and I plan to try it instead of felt. Haven't done it yet.

Curl