45/70 Marlin@50-200yards

[Cheesehead]

I am going to try a cowboy rifle match at the local gun club this week. Steel targets of various sizes at ranges from 50-200yards, ten targets in total for a total time. This sounds like great fun. Put a peep sight on my 1895 Marlin and am loading some medium power rounds. I selected IMR 4064 for its greater case fill and am topping the round with lazer cast 350 grain slugs. Reloads are on the clock. Any one familiar with this type of competition and/have any recommendations.

Cheese

[PlacitasSlim]

50 to 200 yards seems like a lot of variation for a 45/70 and a peep sight. If you look at the trajectory for a 45/70 it looks like a rainbow. Mine with a peep sight is sighted in for 100 yds and is 3" high at 50 yds, but is about 12 " low at 200. For that much range variation you need one of the ladder type sights marked for the different ranges.

[Bitterroot Bob]

Sounds like a great way to spend the day!
Last year I started experimenting with Trailboss powder in rifle cartridges. Large blackpowder cases like the .45-70, 38-55, and .44-40 have too much volume to allow good smokeless powder density. The Lyman books recommend charges of as little as 10 grains of Unique to power 400-grain bullets out of the .45-70. But where is that pinch of powder in relation to the primer from shot to shot?
Trailboss is so bulky that I was able to create a really fun plinking load with 405-grain FN's with it. Use the maximum published data and you will get about 1200fps and very little recoil. Accuracy is on a par with 65 grains of FFg. Give it a try.
Having a chronograph and a set of ballistics tables are important when learning to shoot a bullet with a mortar-like trajectory. You'll need a rear sight with a lot of quick adjustment if all loading and shooting is on the clock. I'd recommend a carbine ladder sight. Dixie Gunworks sells a replica Winchester carbine ladder in their catalog. I am using it with great success on a M94 Winchester .32 Spl.


Bitterroot