I am having the hardest time getting rid of my unburnt powder problem in my 45 70. It is a Marlin 1895 SBL with the short (18"?) Barrel. I am loading 300 grain Hornady Hp bullets with IMR 3031 powder. Even at 54 grains powder (1725 fps) I can dump a little bit of powder out of the casing after I shoot. I am crimping my loads as well. I am using CCI 200 primers. Am thinking I might need to try the CCI 250 instead. Also thinking I may have to try a faster powder due to the short barrel. Was thinking Reloader 7 but it looks like it may not be that much faster than the IMR 3031. Any ideas?

I use 48.5grs Imr 4198 with 300’s.


I used to shoot RL7 and had burned but not consumed kernels like you’re talking about. It shot so good it never bothered me. I went away from RL7 because it was hard to find around here.

The short barrel isn't the cause. All the powder that going to burn, burns within a short distance in front of the chamber, because that''s where pressure is highest.

Instead it's lower pressure than the powder was designed for. In my 32" barreled trapdoor Springfield a 1300
fps load of IMR4895 with 400-grain bullets shoots great--but there are still plenty of unburned (or only partially kernels, because the load isn;t anywhere near the 50,000 PSI or so IMR4895 was designed for.

Why is it a problem? Is accuracy poor, or inconsistent?

Accuracy is about 1 1\2 at 100 yards. That is pretty good for this gun. I guess if it shoots good I should not worry about it. Truth of the matter is thus is my brothers gun and he doesn't like the unburned powder. Guess I need to just tell him that it does not hurt anything.

Or switch to 4198 and please both of you.

Ken Waters Pet Loads lists a case full of 4831 as an accuracy powder in the 45-70. (trapdoors too) Many experienced guys over at cast boolits have experienced outstanding accuracy as well. And it leaves a lot of scorched kernels in the bore, but the consensus seems to be that no one is particularly concerned about it. Some high dollar collector grade guns involved too. If you get 1 1/2 groups with your load, I'd stick with it.