Duplex loads

[SiringoMN]

Last year, before I had my '76 in 50-95 re-barreled, I played around with duplexing.  Has anyone else had success?  I use 4759 and regular Goex ffg. My notes say 8 grains of smokeless and 70 grains of black. In theory that should be a 92 grain BP equivalent. I used the AA 350cl bullet and a WLRM primer. I fired 20 rounds with no fouling problems, which is my goal.

Duplexing requires load development to get the right combination for accuracy. It won't be as good as pure black, my goal is to be able to shoot 20 rounds without loss of accuracy.

Just curious on others experience.

[ndnchf]

I'm curious how you are calculating that this is 92gr of BP equivalent. I've never heard of a ballistic lab or other reputable source that tested the effect on burn rate and pressures when 4759, or any smokeless powder was combined with black powder. I've made duplex loads myself, but never had solid data to base a calculation on.

[SiringoMN]

I'm basing it off of J. P. Wolfs book on loading the 45-70 to duplicate military loads. While it may not equate to the 50-95. Each grain of the smokeless was equivalent to 2.7 grains of black (regular Goex) in the 45-70. Usually the percentage was 7 to 10% smokeless and then fill the case up to the base of the bullet with black.  Light compression.  Part of the key is to check velocities. I have not done this yet to any degree with the 50-95. I did chronograph the load I mentioned for the 50-95 and got in the middle 1400's with a 350 grain bullet if I recall. I haven't a clue on pressure.

[ndnchf]

Thanks. I have that book, but don't recall that bit of info. I need to pull it down and have a look.

[SiringoMN]

I have other friends shooting 50-70's and duplexing them. But those loads do not shoot as clean as the 45-70. My 45-70 loads using wolf's 405 rifle load are spotless.

It seems duplexing of the 50-95 is uncharted territory.

[greyhawk]

Last year, before I had my '76 in 50-95 re-barreled, I played around with duplexing.  Has anyone else had success?  I use 4759 and regular Goex ffg. My notes say 8 grains of smokeless and 70 grains of black. In theory that should be a 92 grain BP equivalent. I used the AA 350cl bullet and a WLRM primer. I fired 20 rounds with no fouling problems, which is my goal.

Duplexing requires load development to get the right combination for accuracy. It won't be as good as pure black, my goal is to be able to shoot 20 rounds without loss of accuracy.

Just curious on others experience.

Have not duplexed my '76 but I do it in my 86 (45/70) and a 92 (38/40)

I tried sr 4759 and imi 4227

settled on the 4227 as it gave me better accuracy in the 45/70 (also takes less room in the case) my sr4759 was likely 40 years old and the 4227 relatively fresh so that could have made a difference

The 45/70 duplex load is 6 grains of 4227 + 64 grains of FFFg + 335 grain LEE (from the 405HB mold) + 45thou HDPE wad - gave me a whisker over 1500fps with an ES of 7 FPS for ten shot string ---that worked good!