Loads for 45-70

by Woodsbum

Finding reloading data on generic or lesser known bullets is not an easy feat. Most of the time you have to work up your own data. A few months ago I found some 405 gr cast bullets for my 45-70 and spent a lot of time looking for some reloading data so I can get them out and test them. Unfortunately, the data I found was never inclusive of any powder that was available so I have had to back up and “punt.”

In researching other bullet loads I found some data on the use of IMR 3031 that I thought I could use to establish a base and work up some loads from there. While working on this, my father did the same thing with the use of IMR 4198 using the same bullets. Since we had two different powder loads to evaluate, I talked him into getting out his old chronograph and we went out to the gravel pit to do some testing.

First off, his loads are using 40 gr of IMR 4198 and the same 405 gr cast bullets. Since I had not done any real testing yet, I went ahead and put together some ladder tests from 42 gr of IMR 3031 to a max of 49 gr in .5 gr increments. We chronographed each shot to look at the velocity and then checked for pressure signs. Again, all this work was based around finding a good load for the 405 gr cast bullets we picked up. Here is what we found.

My father’s load using 40 gr of IMR 4198 shot at 1702 fps.

My loads worked out as such:
42 gr IMR 3031      1271
42.5 gr IMR 3031   1406
43 gr IMR 3031      1434
43.5 gr IMR 3031   1461
44 gr IMR 3031      1482
44.5 gr IMR 3031   1508
45 gr IMR 3031      1549
45.5 gr IMR 3031   1582 and the primer just began to flatten just a touch
46 gr IMR 3031      1586 and the primer flattened even more
46.5 gr IMR 3031   1589 and the primer flattened as far as I felt was truly safe for brass/rifle

The best range load for this powder, bullet and rifle seems to be around the 45 gr of IMR 3031 mark. Even though I now had loads for 45-70 using these 405 gr cast bullets, I wondered what Hornady 325 gr Leverevolution ammunition would chronograph. It was travelling at 1825 fps. Again, this is 80 gr lighter bullet than the ones we were testing.

Since we were out there I also chronographed my father’s 300 gr hollow point loads. He was using 46.5 gr of IMR 4198 in these cartridges and they came out at 1875 fps.

Lastly, there were some plinking loads that a friend of mine made. He somehow found some 150 gr cast bullets and loaded them up with 11 gr of Trail Boss powder. These seemed to be a very light and fun round to shoot. They were like oversized .22 lr with regard to recoil and sound. Again, we decided that these would be a great small game round and were an absolute blast to play around with. The speeds of these ranged between 1262 and 1283 fps.

My father also brought out his 45-70 Sharpes 34″ barrel rifle to play with. I have excluded the data from that since it really made my little Marlin 1895 GBL look anaemic with regard to the speeds these loads produced.

All said and done it was a great outing. We had a great time and I found that I need to procure myself some IMR 4198 for these heavier grain bullets.

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