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Old 10-11-2010, 02:33 AM
borealis borealis is offline
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Join Date: Jul 2006
Location: Anchorage, AK
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(Note to the reader: Use these loads at your own risk. The loads below are developed from Cast Performance's load data (405 g hard cast) and Hodgdon's (350g jacketed loads) and work well in my gun but may not work so well or safely in yours. Always work up from the minimum published loads and watch for over pressure signs. Please also keep in mind that these loads are developed in a cooler climate - Alaska and will probably be at higher pressures in warmer cliimates)

Disclaimer aside, I also own a Marlin .45-70 gov with a MicroGroove barrel (22 inch) and reload my own ammunition. Up front, I recognize that you are casting your own bullets and do respect that. I have a load worked up with 46.2 grains of IMR 3031 and a 405g hard cast bullet that will easily group inside 2 and a half inches at 100 yards. The bullets are sized at .459. I've run them over the chronograph at 1480 fps on cooler days; 45 degrees and about 100 fps faster on warmer Alaskan days - about 65 to 70 degrees. The IMR 3031 seems a bit temperature sensitive. This is a fun load for smacking the gongs with!

But in terms of what my rifle seems to shoot best with, I really do like the IMR 4198 but I use it with jacketed bullets in the 350g weight range. I think it excels with this bullet weight. At 49.5g of IMR 4198 with the Hornady 350g FP, I have no difficulty clustering 5 shots under two inches at 100 yds. This load is taken from Hodgdon's data and stands at .5 grains less than maximum. The load runs at about 1993 fps average at 65 degrees Fahr. and drops about 40 fps when the temps run down in the low 40's. The bullet drops about 10 inches at 200 yds. I have a similar load for a 350 grain Swift A-Frame at 49.1g of IMR4198. I've noticed pressure spikes when I run any higher than 49.2g of IMR4198 under this bullet so I consider it to be at max load. The bullet appears to have a longer bearing surface than the Hornady 350g bullet, so the pressures are probably higher. It runs a little slower (1972 fps), but it is the hunting load that I carry when in in brown bear country.

BTW - putting a Limb Saver recoil pad on my rifle made extended shooting sessions much more enjoyable. I put 10 of the 350g loads and 18 of the 400 grain loads through the rifle today without aggravating my shoulder at all. It has seriously knocked down any tendency to flinch at the bench for me.

Last edited by borealis; 10-11-2010 at 03:36 AM. Reason: corrections and clarifications of data
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