Specific load for my 45/70

[Art]

Hello, I need information for this setup:

Marlin Guide Gun
405 grain cast bullets with gas check (from the Bullet Barn)
H322 powder

I've searched but can't find information on this specific combination. Anyone know what is a good starting load and safe maximum load for this particular setup? Thanks.

 

[shotgun12G]

The following info is from the IMR on line load data.

400 GR. SPR JFP Hodgdon H322 .458" 2.540" 50.0 1767 23,700 CUP
55.0C 1984 39,200 CUP

I would back it off some to prevent too much leading!
The B.B. 405 Gr GC bullet performs best at about 1600 fps. Having said that, I load them up to 1800 fps for hunting. Very accurate bullet!

Shotgun

 

[wapitiwhacker]

Just curious Art. Have you weighed any of your 405s? I have some of the same bullets, and weighed them to see how close the tolerances were. I was surprised to find that they are in fact 420 gr bullets (maybe my scales buggered). I've never worked with cast bullets before, so I'm kinda scratchin' my head here. Are the bullets in fact 405s before they add the gas check? Even if that is the case should we not be looking at 420 gr. load data? (Couldn't find H322 so I'm working with H4198)

You might find this article of interest. There is 405/H322 load info in there.
http://findarticles.com/p/articles/mi_m0BQY/is_9_50/ai_n6125519/

 

[H4831]

The weight change you are talking about, 405 or 420, is actually nothing. That is only about 3%, and you almost have to use commercial alloy to keep within this range.
In other words, if your alloy is nearly all lead, it could weigh, maybe 425. If it is hard cast, meaning less lead and more tin and antimony, it may weigh 390, or less. Easily. So don't get hung up on them weighing other than 405 grains.
Also the loads you are talking about are probably far under being any danger to a Marlin. Thus, you will likely never know whether the bullets weigh 405 or 420.
For loads that are actually light for the Marlin, but a bit whumpy on the shoulder, I get good accuracy with 45 grains of 4895. A load that is just a little lighter, but accurate and into the same group at 100 metres, is 33 of 4198, with bullets of about 420 grains.