Tom's computer pages

April 6, 2025

The 45-70 and H322 powder

I am still searching for "moderate) 45-70 loads.

The problem is powder availability. If I could just buy H4198 or any of the other powders that have documented reduced loads for lead bullets, I doubt if I would be interested in H322. Well, I actually have another motivation -- I have 2 pounds of H322 -- and I see that it is commonly available.

To my surprise, I looked through my original Speer manual (1994) and found this load in the trapdoor listings for a 400 grain jacketed bullet:

H322   350 JFP 37 grains  1086 fps

Back in March of 2009 I made some of my first loads using a 350 grain jacketed bullet and 45.5 grains of H322. They were pretty stout. This was the minimum load from my Lyman 49 (and Lyman 50) in the Marlin section. This manual shows H322 loads in the trapdoor section as well, and shows:

H322   350 JFP  38.5 grains 1331 fps
Varget 350 JFP  45.0 grains 1401 fps
Varget 405 LC   42.0 grains 1258 fps

Now, some loads from the Marlin section:

H322   350 JFP  45.0 grains 1552 fps
H322   405 LC   43.5 grains 1469 fps
Varget 405 LC   49.5 grains 1591 fps

I have plenty of Varget, and wondered if it might be a candidate, but H322 looks like a better option.

The burn rate chart in my Lyman 50 shows H322 as a significantly faster powder than Varget. H322 is near H4198 and Benchmark on the chart and is even faster than H335.

Cast versus Jacketed

The game here is to find published loads for the same weight bullet, cast lead and jacketed, using the same powder and to compare them. Here we go from the Hodgdon 2024 booK:

Varget 300 LC   45.0 grains 1599 fps
Varget 300 SIE  57.0 grains 1770 fps

The above is a poor comparison as the jacketed load is clearly more aggressive.

IMR-3031 300 LC   51.7 grains 1839 fps
IMR-3031 300 SIE  56.0 grains 1884 fps

And:

IMR-8208 300 LC   51.2 grains 1723 fps
IMR-8208 300 SIE  54.0 grains 1728 fps

Here we have two loads that give the same velocity for jacketed and lead bullets. Note that the powder charge for lead is 4.3 grains less and 2.8 grains less respectively, compared to the jacketed.

So a person might conclude that he could reduce a jacketed charge by 3 grains for a lead bullet and get similar velocities as published for a jacketed bullet of the same weight.

Consider the H322 load we started with. We could load 37 grains of powder under a 350 grain lead bullet and see what velocities we get. We could also load 34 grains (3 grains less) and see what results that gives.

Lyman Cast Bullet Handbook

I got this, expecting to find a treasure trove of loads for 300 and 350 grain cast bullets. I was disappointed. As near as I can tell, every load in this book is also in the Lyman 50 which I already have.

The book may be worth the money paid for the articles up in the front rather than load data.

I was doing searches on whether jacketed bullet loads could be used for cast lead bullets of the same weight, and people kept recommending the CBH (rather than answering the question). The answer seems to be, that in almost all cases you can use a jacketed load for a cast lead bullet, but definitely not the other way around. You can probably reduce the jacketed load by a grain or two for use with a cast bullet. But there are risks any time you aren't using a published load, so don't say that I didn't warn you.

Comparison to H4198

Such comparisons are questionable, but there must be some reason that every load manual has burn rate charts. First of all H4198 is a well known powder for somewhat reduced loads for the 45-70. Both H322 and H4198 are extruded extreme powders from Hodgdon. They sit almost next to each other in the burn rate chart.
The Hodgdon "magazine" load manual shows:

H4198  300 Cast LFP  30.0 grains  1390 fps
H4198  385 Cast LFP  28.0 grains  1302 fps
H4198  405 Cast LFP  27.0 grains  1251 fps

Given lead bullet loads like this, it is easy to see why H4198 is a sought after powder for the 45-70.

Some tests

I loaded 34 and 37 grains of H322 with a 350 grain plated Berry's bullet.
This is what I got:

H322  350 plated Berrys  34.0 grains  1369 fps
H322  350 plated Berrys  37.0 grains  1491 fps

These were substantial, but not uncomfortable to shoot. After this I decided on 35 grains as my "standard load". Remember that the original black powder load gave 1350 fps.

Conclusions

I had thought that Varget and H322 might be comparable, but they definitely are not.

I am quite interested in the 37 grain H322 load for a 350 grain Jacketed bullet and will try it with some of my 350 grain Berry's plated bullets. I will be tempted to also try loads with 34 and perhaps 30 grains of H322.

Speer says that 37 grains of H322 gave 1086 fps with a 400 grain jacketed bullet, so this is hopeful for a civilized load using an available powder.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org