Duplex loads

C

condor bravo

New member
Late yesterday, only briefly, there was a new thread titled, I think, "Mixing Powders" that was rather oddly worded, leaving itself open to perhaps ridiculous replies, something that we would have had a lot of fun with. However the thread has been removed, perhaps for the best. While the author did not use the correct terminology, he may have been referring to duplex powder charges, something that I think has been discussed previously on this forum and not at all recommended by the staff and most everyone else. Basically I think it involves loading some slow burning powder and then topped off with a faster powder. This comes under the category of "don't try this at home". Perhaps I should have just left sleeping dogs lie, but the topic does seem to be one of interest. The poster seemed to be referring to completely mixing two powders rather than duplexing. I suppose by mixing 4350 and 4895 you end up with 4395. Like by mixing two half cans of each you are conserving on shelf space. ;)
 
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The Ackley books from the mid 1960s are the only thing I have read about duplex and triplex loading.
I think they layer, and not mix. Some have a piece of paper separating the powders in the case.

It seems they put 2400, Unique and Bullseye in 45 Colt to make something like a 454 Casull.

The military has done it with artillery.

The odd thing is that the fast powder is put next to the bullet, not the primer.

I seriously doubt that one can mix 2400, Unique, and Bullseye and get a higher velocity in 454 than with H110/W296 or LIL'GUN.

So the idea may be obsolete for handloaders.... But I have wondered about Lapua 308 Palma brass with small primer pockets necked down and turn the necks to 260 cannot get going with small magnum rifle primers and a full case of H4350... Maybe add some Bullseye?
I never tried it.
 
CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
The topic is not taboo, if it is discussed meaningfully and responsibly. The poster mentioned seemed to be a pointless troll.
Very slow powders can be used in various calibers by adding a booster charge of a small amount of a faster powder. The typical scenario is 3 grains of (Unique to 3031) at the primer, topped with (WC872, 870, etc.), to fill the case to capacity.
Some proven data is here: http://www.castpics.net/LoadData/Surplus/default.html
This is only for those with years of reloading experience. The (WAY) slower powders are not going to blow up guns. But there is some risk of sailing uncharted waters. You can do a search on duplex loads. Some of use have done this, and posted about the results.
Ackley was trying for faster bullets by putting faster powders on top of slower. I believe he also wrote about destructive testing of firearms. ;) That is NOT what we are talking about with the slower surplus powders. In the latter, the goal is to get the slow powdwers to burn completely, without a trail of coal down your barrel.
 
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Mixing Powders

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
As to mixing rather, than layering, I have done that with WC872 and WC844 up to around 25% WC844. It worked OK, but nothing special. It is labor intensive. The question that I cannot answer is WHY?
Especially since good powders are readily available again.
 
Duplex loads...about the only exposure I've had to them was reading Skeeter Skelton's columns in 'Shooting Times' where he had a lot of fun with them.

But maybe, (I sure don't remember this for sure) he did mention a couple of valid loads using them too.
 
I would worry about the powders changing position over time. A fine, fast powder at the bullet base might mix with a coarser, slower powder, changing the effective burn rate.
Or a mixed charge separating into separate charges.

High risk, low reward.
 
I read a good thread at castboolits where a guy fell into a large surplus of powder that was too slow for his .223. he seemed to be a very experienced reloader and definitely was doing things that I am not brave enough to try, but he was use just a couple grains of a fast pistol powder to get the "too-slow" powder a jump start to get better combustion. it was apparently working for him, was a good read, just not something I need to experiment with.
 
Though I have no experience with them, and no intention of trying, there are Duplex recipes for at least one caliber in the Ideal Handbook #38...

I am NOT recommending anyone try them, just pointing out that they were 'published' loads at one time...
 
I've used a triplex load in my T/C 454 Contender for over 30 years. The purpose of the triplex load was to tame the recoil, muzzle blast, while supporting maximum performance and enhancing case life. Because of the chances of overcharging a case I would never encourage anyone to try it nor would I give out my recipe for this load.
 
Skizzum touched on the aspect of duplex loads that I've heard about . A guy at my local range was talking about how he came across a large amount of powder at a great deal . Problem was it was slow or maybe very slow for a large case . It's been awhile but I want to say 50BMG or something . He said he would put 10 to 20 grains of a faster rifle powder in first then filled the rest with the slower powder . He claimed that helped get a more complete burn of the slower powder because the prime alone was not enough. Like I said , It's been awhile and I don't remember the specifics of the cartridge or powders but that's the general understanding I got from the conversation .

Oh , was this the thread about mixing powders ? http://thefiringline.com/forums/showthread.php?t=565842
 
Just goes to show if you live long enough you will learn something!

The only duplexing I ever heard of was with black powder. That folks have done it with smokeless is news to me!

As for the guys with the large lot of cheap, slow, powders, who then put life and limb at risk duplexing just so they could shoot that stuff up, my initial reaction of amazement :eek: yielded to what another contributor puts in his signature line, "it is amazing the amount of toil (and risk) and angst a cheap S.O.B. will put himself to just to save a penny." LOL ;)

Whoever these guys are, I would hope that they alert the innocent shooters nearby at the range BEFORE they touch off those rounds so that those folks can clear the area in case of catastrophic failure.
 
Actually, I was referring to a different thread that was removed. I guess you didn't see it, and it is gone now.

Old August 13, 2015, 05:50 PM #48
condor bravo
Mr Entropy's initial post, that was deleted, seemed so much off the wall and phony that ...
Click to expand...

I do think these threads are pointless hot air, designed and intended to generate reactions. They are NOT about practical reloading issues.
 
The first thread was closed. A second thread from the same poster was allowed and remains open for discussion.

What I (and some others) understood from the OP was he was asking why mixing (blending) powders was a bad idea. And, we told him.

Duplex and Triplex loads are NOT the same thing. They are "layered" charges.

I understand Dick Casull did some work with them developing his .454 Magnum. I heard at one point he had a load of X gr of bullseye over the primer, then XXgr of Unique on top of that, then XXXgr of 2400 filling the case.

Apparently it did work. Also, apparently not enough difference from a single powder (in that case) to make it worthwhile. I understand factory .454 are loaded with a single powder. (please correct me, if I'm wrong).

IF the layers of powder fill the case (slightly compressed?) I wouldn't worry much about them "blending" together, because there isn't room for them to move and mix. IF there were air space in the case, then absolutely normal handling would result in a blended mixture in relatively short order.
 
Right, Marco. I did not see that thread.

Yes, hypothetical threads are of little practical value, but theoretical ones are often educational. Just knowing that duplexed loads (either layered or mixed) filled a need and that the need is now filled by better-designed powders (safer, simpler and more practical) is also helpful.

I am reminded of a quote: "The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
George Bernard Shaw (1856 - 1950), Man and Superman (1903) "Maxims for Revolutionists"

And another saying: "The early bird may get the worm, but it's the second mouse that gets the cheese."

Lesson between those two quotes: Watch your step if you are the first on the trail. The wise man learns from his own mistakes. The TRULY wise man learns from the mistakes of others. This is why scientists, before they begin their experiments, research what has been done in the past. This, I believe is what mrentropy is doing.

Good night. Thanks for reading my musings.

Lost Sheep
 
http://cartridgecollectors.org/images/introduction-to-artillery-shells-and-shell-casings/btf4.jpg

I have a shell casing with a tube that runs from the primer pocket to near the top of the case. I am told it was designed for two different powders. I am told the fast powder was loaded on top of the slow powder. Many years ago I remember cutting powder bags. The bags were not numbered, they were on a string. There was not much chance of mixing the order the bags were loaded. When told to 'cut' the string was cut on the edge of the shell.

There are other factors, some powders are position sensitive, other factors, the powder does not fill the case, then there the speed primers burn, without powder the primer can drive a bullet into the forcing cone. Driving the bullet into the forcing cone can complicate a shooters life if the powder burn is not perfect because of other factors.

F. Guffey
 
Gee, Guff, that link goes to an artillery fuze.

Elmer Keith wrote about flash tube experiments he, O'Neil, and Hopkins did just before and during WWII.
He was very proud that the system delivered an increase of 202 fps in .50 BMG without excessive pressure. They called that "Duplex Loading" intentionally to confuse spies. When they started layering powders around the flash tube, they called that "Double Duplex."

I understand Dick Casull did some work with them developing his .454 Magnum. I heard at one point he had a load of X gr of bullseye over the primer, then XXgr of Unique on top of that, then XXXgr of 2400 filling the case.
Click to expand...

My recollection was that he put the Unique in first, then the 2400, then the Bullseye for a "kick." No matter what order, W296 was better... when it became available.
 
Many years ago I cleaned the worst of brass in vinegar, once. I think cleaning brass in an acid is a bad habit, but I used vinegar to reduce tumbling for days. I used straight vinegar, not the good stuff from the table with 15%, I used the 5%.

For most 5% is not good enough, they insist on adding salt and other additives. I have never had a batch of vinegar fail to clean cases in 15 minutes.

Mixing powder: I suppose if one insist on improving the cleaning ability of vinegar they would have trouble applying thee 'Leaver Policy' to powder.


I have increased the time factor when using vinegar by adding water. Old tools: I have cleaned old tools in vinegar, cleaning time goes into hours. Then there were skillets, I had friends that cleaned skillets like mad men.

F. Guffey
 
Gee, Guff,
Click to expand...

I hope you do not think I was trying to sneak one by, I have that fuse with the parts that it screws into it. I also have a shell with the extended flash tube.

Without the tube the fast powder had to be loaded against the primer.

F. Guffey
 
I'm sure someone has experimented with small arms cases, but I know for a fact that the 105mm main gun round for the M60 tank uses a "primer tube / flash tube" that extends about half way up into the powder space.

I'm sure its filled with something very ignitable (possibly black powder??). The idea is to distribute the igniting flash deep into the powder mass, to give better, more reliably consistent ignition.

We used to unscrew the tubes and cut the cases off, 3-4-5 inches above the base, and notch the sides with a hacksaw. Makes a fine desk ashtray that NO ONE will knock over by accident! ;)

Also a decently lethal impact weapon if your hootch is overrun...:rolleyes:
 
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