Anyone got tried and true data for hard cast with IMR4198? Have run low on my 300 JHP bullets and want to try some 405s that I've had for many years.

My data for the 45-70 is pretty limited since I never got into the big boomers too much. But I actually did try IMR-4198 and 405 grain hard cast bullets, even if only for a very short time.

From a 15" SSK Contender barrel, I was getting 3-shot, 100 yard groups of 1-1.25" using 32 grains of propellant. I also tried 32.5, 33 and 33.5 grains but did not get acceptable accuracy. My old notes indicate the pressures seemed pretty mild, though that's a subjective term when you are sending that much lead downrange.

I was going to try some filler material to see if that would improve accuracy (though I had no ignition or deviation issues) but never got around to doing so as I did not keep the barrel around very long.

My sons are shooting 28grs of I4198 with 1 gr of filler pushing 405gr cast bullets out of their Marlin guide guns (18.5" barrels). I chronographed the load last week. 1,200 fps.

Thanks guys.

Just as an aside, I found 4759 to be a very clean and effective powder for short 45/70s. Start at about 25gr under your 405s and see how you like it.

Hodgdon has some wild loads with H4198 and 405 grain bullets. IMR4198 is pretty close to it.

Wilson,

I believe I have some loads that might work out well for you. I'm still on vacation and won't be home until next week to look up the loads for you. This is the first time the wireless internet at our KOA campground has stayed up long enough for me to sign in. Also, Lyman has some good cast loads listed with that powder if my memory is functioning.

You have to be careful with the Contender frame there Ty, you can get into trouble with it easily enough.

45-70 Government, 15" barrel
405 grain Cast LFN, 2.54" COL
Winchester brass
CCI-200 primer
30 grains IMR4198 ≈1200 fps and 17,000 CUP
32 grains IMR4198 ≈1280 fps and 19,000 CUP

processing..........

Thanks again guys!

Wilson,

Sorry for the long delay, we got back into town late last night.

My Lyman 47th ed lists a 405 gr with IMR 4198 and a start load of 21.5, and a max load of 28.5 in their Contender section. In the same book, in the Springfield trapdoor section, they list a 420 gr bullet with a start load of 21.5 and a max load of 28.5. For a 385 gr bullet they list a 23.0 gr start and a 30.0 gr max in the same trapdoor section.

Hodgdon's website lists a 405 gr bullet with IMR 4198 and a start load of 30.0 grs and a max load of 32.0 grs. in the Springfield trapdoor levels chart.

My own personal load range I tried was from 27.5 grs to 31.0 grs of IMR 4198 and a Meister 405 gr bullet, seated long to just off the rifling of my 14" factory Contender barrel. I used "standard" Remington rifle primers in all my load testing.

The 27.5 gr load was the worst group, and the groups got progressively smaller until I hit my 31.0 gr load. That was the largest charge I fired from my barrel, and it was also the best group. It measured 2" x 2.5" and that included one called pulled shot, in a 5 shot group. I considered that pretty decent, especially with my eyesight and a fixed 3x scope.

At no time did I experience any pressure signs at all, or have any problems with sticking cases or extraction problems. Recoil was moderate with the IMR 4198 powder.

When I fire smokeless powder from my Contender barrel, I always stick to "trapdoor" level loads.