Home Forums Reloading Big Game Rifles Is anyone using Duplex loads

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Many years ago duplex loads were somewhat popular. Is anyone still doing that? With the wide selection of powder available to the reloader today would there be any advantage in mixing powders?

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I think the only advantage would be to the reloader's family, assuming that the deceased was adequately insured.

Stated more seriously, I cannot think of anything that violate the principles of safe reloading more than mixing powders together. The wide selection of powders assures that such mixing is not necessary.

Haven't seen that in years. The newer powders are probably some of it but I also think afordable portable chronographs have had more to do with it. People discovered all that fuss wasn't producing what they thought it was. I do know one guy that still uses Elmer Keiths duplex system but he is down to only one caliber loaded that way. Chrono's ruined that for him, plus he has decided it's a heck of a lot of work modifing cases. Do know a couple of guys that still run a litle smokeless in their black powder loads for cleaner burning, but even that is fadeing away. Can't help but think that overall it's a good thing.

When I was young, just getting started in handloading, I did use duplex, and tri-plex loads in an S&W Mod. 28 .357. Never had a "catastrophic" failure, but consider myself lucky. Probably eroded the forcing cone 1/2" up the barrel in the process, but I can blame much on the ignorance of youth.

I wouldn't recommend the practice! Just say "No"!

It was an interesting thing to read about doing when the 454 Casull was being developed. Like many things, the theory sounded great. I guess it was sometimes a bit *POW-ker-BOOM* hard on equipment though.

While I am sure that Elmer probably utilized mixed powders during his extensive strength-testing of revolvers, his use of the term "duplex" involved threaded extensions to carry the primer flash toward the front of the powder charge rather than the mixing of powders.

No just no, Hell no. I don't do meth either. I'm not going to start either one.

To the OP's original questions:

Absofrickinglutely NO! Twice.

Thrice!

I've never lived in a duplex, but when we were first married and lived in an apartment, I reloaded in the garage.

Elmeer's so-called duplex loads were not actually duplex loads. They were a tube in the case, so that the powder ignighted first at the front near the base of the bullet, instead of at the base
near the powder.

Seems like I remember reading something about someone asking Elmer about mixing powders, what some consider duplex loads, and he didn't like the idea. He thought it was dangerous, too, so I doubt if he ever did it.

I have read of people doing it with hard to ignite powder, but I don't know what type of powder this would be. All powder I have ever used worked just fine from primer ignition.

I don't think powder manufacturers do it, either. I have read that they do blend powders, but the powders are of the same chemical composition, just different lots and with different burning rates. I don't think the powder manufacturers would blend two or more powders of different chemical compositions.

Too much like standing with one foot in a bucket of ice water and the other foot in a bucket of boiling water, hoping that it would average out as comfortable.

I duplex from time to time. 5grs of 4759 with 70 grs of bp under a 520 gr paper patch bullet in a 45-70 sharps.
Makes as much smoke as a regular bp load, but leaves fouling in the barrel closer to what you get with 5744.

Mixing powders is extremely dangerous, unnecessary, and very foolish!

So the answer is NO!

Does anyone have actural experience with Duplex loads being dangerous?.
Good Luck!

What about if you were to charge a case and seat the bullet, and then realize that you hadn't seated a primer... and then without disassembling said cartridge, go ahead and seat that puppy. I think that would be close in seriousness, although I'm told the explosion of an unchambered round has significantly less force, and the reciever wouldn't become the scalpel for providing you with a face lift like a duplex might cause, but that brass case and bullet might...

I don't believe that testing is necessary here; no charts, no graphs. I won't do either...

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What is the matter with you guys? I ask a simple question about the history of duplex loading and if any experimentation is still being done. I get 2 or 3 straight answers and the rest of you fly into a tirade about the foolishness using duplex loads. Now, if anyone is doing any work with duplex loading they will be afraid to speak up for fear of being chastised. Thanks a lot.

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J, there's several folks still messing with duplex loads in the bpcr and schuetzen matches.Mostly you replace 10% or less of the bp charge with smokeless. The older Lyman/Ideal reload books talked about these type loads.
You'll probably have to go to one of the sites that deal more with that sort of thing. That way you won't get all these grizzled ol veteran benchrest accuracy freaks so worked up.

I have no experience with that process, and think it's best left to those with the tools, pressure monitoring equipment, and facilities to safely investigate all of the ramifications. Resulting pressure curves may not track layman expectations depending on how or if powders are mixed, and if not mixed, stacked in a load. In applied situations where one carries rifles etc for extended times, the powders might also have the ability to sort themselves if gain size and/or relative density vary significantly.

Given the array of powders available today, I don't think one can safely make a substantial gain in velocity or devise some new burn/pressure pattern that will turn the world upside down.

Do people do it and get by? Yes. Looking at all of the web videos that cycle around though, people do all kinds of obviously risky stuff. Some live through it and some don't. The rare instances I've actually heard of were folks short on supplies, and they mixed something like 4320 and 4350 to get a box of 20 loaded for the short run.

Just let me know though if we're at the range, and I'll not use your ammo or venture near your bench. We aren't baking bread here, so when dealing with high pressure explosives, I think it's best left to the experts, 1Minute

More of you have experience with this than you might think. Take a look at AA9 or AA5 under a microscope. They are mixtures of two different powders.

Denton:

If they are different, wouldn't they have to have the same chemical composition to be mixed?

The only reason I can think of for a powder manufacturer to mix powders would be to alter the burning rate for cannister powders, and even then, it would have to be powder of the same type, just a different lot.

Could they make a powder with the same chemical composition, but each of them have a different appearance, as indicated in your post?

Do you know first hand of any lab actually doing tests on cartridges using mixed powders under controled conditions, like a pressure gun and chronograph?

In all my years of reloading, approaching 50 now, I have heard, NEVER, NEVER, NEVER mix powders, and I never have, but I wonder if tests have ever been made to determine the results of doing it. Even powder manufacturers say not to do it, so it makes me wonder if anyone has actually tested the practice.

And, no, before anyone chimes in, I have no intention of trying it, unless someone is kind enough to donate a pressure test gun and a safe enviorment to make the tests.