.45-70 Duplex loads?

[hc18flyer]

I recently found 3.5 # of Goex 1 1/2 X black powder. I would like to try some duplex loads in our Browning high wall. I have both 4227 and 4759 powders. I have the Lee 405 grain pb mold, and could cast some in 20 to 1 or 25 to 1 alloy? I have been ready old posts on duplex loads and have the Lyman Cast bullet handbook. hc

[BLAHUT]

Try magnum primers first and see ????

[M-Tecs]

As a kicker I've only used 4759. It really helps with fouling control.

https://castboolits.gunloads.com/sho...r-duplex-loads

https://castboolits.gunloads.com/sho...0-duplex-loads

https://forum.castbulletassoc.org/th...x-45-70-loads/

[Nobade]

I'd use the 4759. That bullet doesn't carry much lube so you'll pretty much need to duplex to get it to work with BP. Don't go above 10% with the smokeless and use minimal compression unlike straight black loads.

[indian joe]

I tried both and came up best with the 4227 (by a decent margin of accuracy) 7 grains ----4227 is very close to equal density to black powder where 4759 is much more bulky (my 4759 was really old so maybe that made a difference but I would not go past 4227 for duplex - also using it in a 38/40 model 92)
Rifle is Chiappa 1886
Over the chrono I got single digit Extreme Spread with this load

[freakonaleash]

I have used 4227, 5744, and 4759. Always less than 10%. Usually between 4 to 7grs depending on the cartridge.

[NSB]

I respect those that like to shoot black powder and be traditional. That being said, if you’re going to add smokeless into the mix, why not just use smokeless and skip the black?

[hc18flyer]

I respect those that like to shoot black powder and be traditional. That being said, if you’re going to add smokeless into the mix, why not just use smokeless and skip the black?

Because I like blackpowder and I have 3.5 # of 1 1/2 F. Does me no good on the shelf? I have read that a duplex load can help clean up some of the fouling? Should be fun shooting and use some of it up. hc18flyer

PS- It will be fun to watch my Grandson and nephew's reaction when they fire one for the first time!

[ascast]

What Nobade and Indian joe said. Start low and increase unt fouling is gone, or 10%. I have shot a little over 10% to get clean n a trapdoor with no ill effect. Not sure why 10% s considered the top end. have fun.

[Gray Fox]

In other words, what your saying is for a load of 65 grains of BP, use up to 6.5 grains of the smokeless and deduct that amount from the BP charge, is that the correct relationship? GF

[Chill Wills]

What Nobade and Indian joe said. Start low and increase unt fouling is gone, or 10%. I have shot a little over 10% to get clean n a trapdoor with no ill effect. Not sure why 10% s considered the top end. have fun.

The American NRA - in their rules of competition for BPTR state 10% maximum. Not as a safety issue but as a ceiling, so you do not bring a smokeless load to a BP match. In Canada, their ruling body allows 20% for the same reasons. The older Lyman cast bullet handbook lists Duplex loads for the 45-70 Govt.

[Gray Fox]

OK, here's a question that may draw some flack, can Pyrodex be duplex loaded? I ask because I was gifted a 12# case of Pyrodex cartridge grade that was sitting in a powder bunker under controlled conditions. GF

[steveu]

I have used both 4759 and 4227 in my Trapdoor and my 50-90, both worked well.

[indian joe]

In other words, what your saying is for a load of 65 grains of BP, use up to 6.5 grains of the smokeless and deduct that amount from the BP charge, is that the correct relationship? GF

That works for me --10% is adequate to clean up the BP charge ---more ? would be for a different reason (cheating in a competition maybe????)
I make my BP (2bucks /pound)and buy the smokeless so no incentive for using extra.
With a 10% duplex load behind a 335 grain boolit I get a whisker over 1500 FPS velocity
I like it for the '86

[Castaway]

BLAHUT, I don’t understand your post. He asked about duplex loads and you asked a question about magnum primers. Are you suggesting to use magnum primers with duplex loads? If so, why the question? Please clarify

[indian joe]

I'd use the 4759. That bullet doesn't carry much lube so you'll pretty much need to duplex to get it to work with BP. Don't go above 10% with the smokeless and use minimal compression unlike straight black loads.

I've not changed my compression at all with the 4227 but it does kinda make sense for 4759 seeing that stuff is a tubular (hollow) grain structure

[Larry Gibson]

If wanting to maintain the same pressure and velocity levels with duplex loads you must reduce the amount of BP an appropriate amount to compensate for the pressure/velocity of the smokeless powder. For my replicant m1873 45-70 Government loads I use(d) 7 gr of 4759 under 54 gr of GOEX Cartridge. That maintain the same psi (measured) and velocity as a standard 70 gr load of just GOEX Cartridge. It also blew out most all the fouling out of my long original TD rifle letting me shoot 100+ cartridges w/o wiping, blowing or cleaning. Accuracy remained excellent from the first to the last rounds fired.

[hc18flyer]

Thanks to all for their replies! I understand I need to reduce the black powder charge. It will be my first experience with bp cartridge, so I have some homework to do. And I will have to get lube and vegetable wads(for lack of a better term). Thanks, hc18flyer

[freakonaleash]

If this is your first experience with BPCR I'd recommend you stick with straight black powder.

[Froogal]

OK, here's a question that may draw some flack, can Pyrodex be duplex loaded? I ask because I was gifted a 12# case of Pyrodex cartridge grade that was sitting in a powder bunker under controlled conditions. GF

I recently loaded about 100 .45 Colt cartridges using .3cc of 4227 and 1.9cc of Pyrodex (3F). 200 grain RNFP. Shot 50 of those yesterday through a Cimarron SAA with 4 3/4" barrel. Recoil was a bit more than anticipated but otherwise worked very well. Accuracy was as good as I am.