45-70 Modern Loads

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ligonierbill

New member
I have been loading for an original Springfield Trapdoor for some time: holy black or Black MZ and 405 or 500 grain cast like the old days. But I ordered a Uberti reproduction of the 1885 Winchester Highwall, and am going to add a "modern" load for it. Bullets, of course, are an issue. Hornady 300 gr HP (#4500) are backordered. Beggars can't be choosers.

I would welcome other bullet suggestions, but my main question is powder. Hornady tested typical fast powders, and I do have H4198 and IMR-4198 on hand. Speer tested these also, but they added some medium rate powders, specifically IMR-4320, of which I have a good supply. What are you using?
 
H4198 for 300 and 350 jhp/jsp. Would be extremely careful with the max loads listed in older Hodgen annual manuals for levers, and stick to milder loads.

What velocities are you going for?
 
The lighter the bullet the faster a given pressure accelerates it So the powder has to be fast enough to make gas fast enough to chase it down the barrel without falling behind; in other words, to keep up with the expansion. That's why you'll see some medium speed powders for the lower lever rifle pressures, but not the higher modern rifle pressures. Those slower powders just don't make gas fast enough to get to those higher modern rifle pressures even when you fill the case and compress it.

The next obvious question becomes, well, if I put in a heavier bullet, will that be slow enough for those powders to reach modern rifle pressures? Only if your throat will let you seat those bullets out far enough that their added weight isn't taking up more space in the case. As bullets get heavier they don't accelerate as fast at a given pressure, but, at normal COL, their added seating depth takes up more powder space so they don't have to move as far to double the volume behind them. That means they can accelerate more slowly but still multiply the powder space as quickly as an accelerating light bullet does. I've seen this with the 44 Magnum. As you go up in weight with the really heavy bullets, filling the case 100% with 296/H110 achieves lower and lower peak pressures.
 
The Hornady 350 grn. R.N. and IMR3031 worked really well in my old Miroku 1886 replica lever gun (45/70). Worked up a great, proven, accurate hunting load using those bullets and that propellent.
 
45-70 from Marlin 18.5 in guide gun, twice fired win brass, Fed 210 primer, 2.545 col

300 gn sierra jhp
50 gns H-4198 = 1950 fps ex accuracy
52 gns H-4198 = 2006 fps ex potential
54 gns H-4198 = 2120 fps, poor accuracy, on edge of sticky extraction

rem 300 sjhp, 2.534 col, IMR-4198
46.0 gns = 1880 fps, vg to ex accuracy
47.0 gns = 1900 fps, ex accuracy
48.0 gns = 1960 fps, vg accuracy, slightly sticky extraction

rem 300 gn with H-4198
48.0 gns = 1890 fps, ex accuracy
49.0 gns = 1940 fps, not as accurate or as consistent velocity

The goal was slightly more than fac velocity's, as was not sure how tough the standard 300 gn jacketed bullets were. The av velocity's were estimated on the fly from 3 shot groups. Quickly learned to put better recoil pad on, and not to bother with ultra velocity loads in the light rifle.
 
ligonierbill said:
I have been loading for an original Springfield Trapdoor for some time: holy black or Black MZ and 405 or 500 grain cast like the old days. But I ordered a Uberti reproduction of the 1885 Winchester Highwall, and am going to add a "modern" load for it. Bullets, of course, are an issue. Hornady 300 gr HP (#4500) are backordered. Beggars can't be choosers.

I would welcome other bullet suggestions, but my main question is powder. Hornady tested typical fast powders, and I do have H4198 and IMR-4198 on hand. Speer tested these also, but they added some medium rate powders, specifically IMR-4320, of which I have a good supply. What are you using?
Click to expand...
I prefer H4198 for my 45-70 loads (405gr JSP @ 1800FPS, 18.5" )
 
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