Load Data for Marlin 45-70
 

Having trouble finding reloading data for a Marlin 45-70. I have IMR 4198 and IMR Trail Boss powder and some Alliant #7 to put behind some 420 gr. Cast Precision and some Barnes 250 gr. Can't find anything online or in any of my manuals. Please pm me if you can help me out. Thank you. Min. and Max values will be appreciated.

250g is really on the light side for the 45-70. I'd use data for the 300g loads but start about 5% above the minimum.

Colin

Yes, I agree 250 gr. is definitely on the light side for this caliber, however a friend gave me a box and thought I should try them for fun. Do you have any info for the 420 gr. cast bullets using the powder I have.

closest I can come
 

45-70..........405gr cast/IMR 4198-32gr/1462fps/19000 CUP
45-70..........405gr cast/Trailboss -13gr/1007fps/25600 CUP
IMR reloading manual 2006

As well
 

snoop around on this forum .......castboolits.com
For the 250gr jacketed just use 300 gr data and it will be a little faster but safe.

Lyman Third Edition
 

420gr cast/OAL 2.550" #457193 ......28.5gr/IMR 4198 with a 1/2gr dacron wad
over the powder 5/8" square and 1/4" thick 1267fps/13900 CUP
*****same powder wad not needed 41.5gr/1737fps/28300 CUP
RE#7/40gr/1493fps/13500 CUP..............48.5gr/1828fps/25000CUP
THE WAD IS ONLY USED IN THE ONE TOP LOAD

Trail Boss works fine for reduced loads in the 45-70. For full power loads get some Varget or 3031, It is much easier to work with in this round, produces from 1200 to 1900 fps with the 405 grain bullet safely and excellent accuracy. I have never had much luck with 4198 in the 45-70 and find it is too fast a powder for the heavier bullets. Lots of pressure with low velocity.

Published loads for the Marlin with the 250 grain and the 405, which is close enough to the 420 you are using just work up from min. With cast bullets and no gas check, you want to keep your velocity under 1500 FPS to avoid severe leading issues. If you work up with Magnum primers you will find far less unburned powder left over, especially in the 18" barrel models.

http://www.hodgdonreloading.com/data/rifle

I’m using varget in my 1895 cowboy with 350gr Hornady RN. They are pretty stout loads and rattle your mellon pretty good when bench shooting.

powder in the 45-70
 

I load 44gr of IMR 4198 /Win brass/Fed mag primer/Hornady 350hr FN in my Marlin/4x Leupold and get 3 shot groups of .504" at 100 yards benched.Recoil is brisk.IMR 3031 was the best powder for the 300grHP in my gun.....54gr gave .536" at 100 yards.Flattens deer.

Basically covered by Dean. For years my go-to powder has been H4198 and I would use cigarette papers to stuff the case. But the truth is both 4198's are a bit fast and yes, pressure builds faster than velocity. That's not to say you can't build a good load with either. You can. But since I was turned on to Varget for the 45-70, it's all I use. The case fills up faster, you get good velocity and pressure is startlingly low.

I've got some 405g hard cast gas checked pills that I got from Jet Bullets that are loaded hot enough that the powder doesn't rattle in the case, yet extraction is normal and there are no pressure signs at all on the cases. I'm hoping to get them over the chrony when things warm up here. Wouldn't be surprised if they're poking north of 1900 fps. That's out of my 22" 1895 - no recoil pad on that one.

Colin