Hey Mike, You didn't mention what velocity you're seeing with your load, do you happen to know? I don't handload for my 45-70, but have experimented with some commercial loads. My favorite (and the most accurate) so far is the Hornady LE 325gr FTX load. It shoots very well in my 1895 and very nearly as well in my Ruger #1 in 45-70. (that's a gun I think you'd really like, Mike!)

I also have a couple of 400gr JSP loads that clock (supposed to) 1800 & 1900 FPS respectively. Those are pretty high horsepower loads capable of most anything you'd want or need the 45-70 to do. One of the 400gr loads was my choice for bear over bait. 

I need to get some time and invest in handloading for my .45-70.  I carried mine for protection in the backcountry in AK, and kept it stuffed with a combination of 405 grain JFN and 430 grain LBT Buffalo Bores.  I really wanted to try Garrett, but I talked to Randy and it would've taken a series of miracles and a lot of coin to get him to ship the ammo to me in AK.  Never really pushed for longer range accuracy, as I configured it with ghost rings for close encounters.

Hi guys. New to the site but am really enjoying it. I had a  custom 45-70 built on a Siamese Mauser action. My favorite and best grouping load was 50.5 grains of IMR4198 and a Hornady 350 grain round nose. Never clocked it but figured I was getting about 2,000-2100 fps out of that load. It was a bit much for whitetail but I used it mostly for blackbear hunting. Unfortunately I never got to shoot a bear with it. I could keep three shots touching each other at 100 yards with that load. It got a bit brutal on the shoulder after about 10 shots off the bench but wasn't bad shooting offhand. That load would shoot straight through a filled 50 gallon hot water heater and keep going!!

I had the rifle made for me by a buddy who was going to the Pittsburgh Gunsmithing Institute back in 1985. I didn't have any problem at all with feeding the big rimmed cases. I have heard about other people having problems though. It had a full length Bastogne walnut Mannlicher stock with two schnabels for my left hand fingers to wrap around. It was a beautiful looking gun but I had to sell it last spring due to financial and health issues. Life really sucks sometimes!! It was a real shooter with both 350 grain Hornadies or 300 grain Sierra hollowpoints.Can't remember exactly how many grains of 4198 I was loading under the 300 grainers.

I have had very good luck with 40 grains of IMR 4198 under a 420 cast bullet, the velocity was just over 1700 fps in a Marlin 22 inch barrel. The 18.5 inch guide gun barrel launched the big pills at 1650 fps.

IMR 4198 or H 4198 burned cleaner than any other powder I tried, most others left some unburned powder kernels in the barrel.