Milsurp WC860 in the 45-70

[Bjornb]

I've been wondering how the slow cannon powders would do in my Buffalo Classic, so last week I loaded up a few rounds and headed to the range. I had 10 loaded with the 485 grain version of the Lyman 457121,alloy was 20:1, sized .460 and lubed with Bullshop's NASA lube. WLR primers. I also had 13 bullets left of a batch of Rapine 460-500 cast from Lyman #2, sized and lubed as above. Powder was surplus WC860. 50 grains filled the case to the base of the bullet.

My H&R Buffalo Classic has a Leapers 6X scope.
First I shot the group on the left, then switched to the heavier bullet, shot the low shot before adjusting the scope and shooting the final 12 rounds into the group on the right. Today I brought along the MagnetoSpeed chronograph; the load clocks in at average 1110 fps.

Next up is taking this load to a longer range and seeing if it holds up. Promising so far.

157760

[curator]

Not wanting to open a can of worms, but I have "played" with wc860 powder in my various .45-70 rifles and got a lot of unburned powder and relatively low velocities. Heck, even Fg black powder gave better velocity than a full case of wc860. Then I discovered "duplexing." Where 52 grains of wc860 provided about 1050 fps with my .460/425 grain ACWW slugs, adding just 3 grains of SR4759 over the primer before adding the 50 grains of wc860 (slightly compressed load) boosted velocity to 1320 fps and NO unburned powder left in chamber and bore. (860 flick--be gone!) Accuracy is as good or better, and at this level I am not getting any pressure signs--just nice rounded primers and easy extraction. I tried this first in my Ruger #! before using it in my Handi-rifle and rolling blocks. I have experimented using this technique with WC860 in several other cartridges in strong modern rifles and found it to significantly improve the usefulness of this cannon-grade smokeless powder.

[Tatume]

There is an extensive body of literature on duplexing WC860 in the Canister & Surplus Powder forum. It is worth reading.

[Bjornb]

I have played with duplex loading the 45-70 using both Black Powder and Milsurp cannon powders. No can of worms here; I totally agree with Curator regarding the advantages of this loading technique. The reason for my posting the straight WC860 load was that it gave almost no recoil and it gave me very good accuracy. Yep, velocity was slow, but it was a very pleasant shooting session and each shot seemed to blow out the old unburned powder from the previous shot.