Anybody out there ever play with Duplex Loads? I've read some P.O. Ackley books where he talks about using Dacron to separate different powders. IE. 3 grains of H380 to push 15 grains of IMR 4895. Any experience with this out there?

He also talks about 2400, Uniue, and Bulleye for 454 Casull.

Duplex loads are usually flamed out of reloading forums, but this forum is fairly advanced and open minded.

Too much risk and too little to gain.

Agree on the too much risk.

The only possible use I can see for duplex loads would be a case with a large volume of powder in which powder fowling indicated inadequate ignition. Even in this case, I would not be the first to do it (and probably not the second or third). I'd give others a chance to blow up their guns first.

I would definitely try different primers before I'd try a duplex load.

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The only possible use I can see for duplex loads would be a case with a large volume of powder in which powder fowling indicated inadequate ignition.

There are some examples of reloaders adding a few grains of bullseye immediately over the primer and then filling the case with a powder that will be compressed and this keeps the bullseye in position.

It is claimed that this prevents hangfires in large cases.

Other than that the duplex loads are totally unneeded as there's a powder for almost any burn rate you'd want.

I've used duplex loads in large bore black powder cartridges (43 Mauser, 45-70 and others). For the 43 Mauser, 55 grains of FFg black on top of 7 grains of 2400 results in a load that can be shot all day without fouling.

IN the Westley Richards explora rounds it was pacticed. They got amazing ballistics by igniting pistol cordite with a special primer that has some, I think, 2 grains of fine black powder.

I think that it would be very useful technique but it would be very very dangerous with out a full balistics lab, pressure guns etc.

Nobody has ever found a way to keep the powders seperate. Wads, compression, whatever. If you shake them enough, like in your pickup over some gravel roads, they will eventually cause trouble, or worse. If you shoot them right away they will probably be OK but what happens if somebody else gets their hands on them, not knowing what they are?? Duplex loads may have been a good idea years ago but today we have so many powders available to us that you should be able to find one that will work with just about any case/bullet combination. JMHO

But, I'm sure the question will continue to come up every few years, just like all the other bad ideas from the past.

Ray

quote:

Originally posted by tnekkcc:

Duplex loads are usually flamed out of reloading forums, but this forum is fairly advanced and open minded.

Is that the definition of liberal? roger

Confession time.For a number of years I played with duplex loads..Twice I've ruined rifles. Both of those times I was trying to get balanced loads of 5020 and fast burning powders. I slowly changed the ratio untill it looked like I'd get all the powder to burn. Hit a point where all the powder burned but it was way too much. It happened twice, maybe three times, I guess because I'm a slow learner.Don't think I'll go down that road again soon. roger

We in RSA don't have the variety of powders available to us that US / European reloaders do, so we are forced to get up to all sorts of mischief to get the most out of our rifles. Duplex loads are one of those things.

A prime example was getting the most out of the excellent 380gr Rhino bullet in the .375H&H. S335 was too fast, and S365 too slow. (Both are extruded powders). S341, a ball powder which burns just a touch slower than S335, was also too fast to get the best out of the 380gr Rhino. So reloaders started working with 32gr of S335, followed by 32gr S365, and seating the long Rhino to lightly compress the load.

The load turned out to be quite safe, and got the job done of pushing the Rhino at just about 2200fps, so that's what folk were doing. There are a couple of caveats, namely - load the quicker powder over the primer, then load the exact same weight of the slower powder over that. Seat the bullet to compress the charge. NEVER mix extruded and ball powders. And my own caveat? Leave the experiments to someone else, and only use well-tried and tested duplex loads from an utterly reliable source.

I believe it was the experimentation with duplex loads for the ultra-heavy .375's which triggered Somchem (our powder manufacturer) to develop S355, an extruded powder that does what the 'duplexers' have always been doing, at their own risk.

Duplexing is an excellent way to see if you can blow up a firearm as you are clueless on what you are doing...

too many " what if" variables...

one local guy at the range blew up 3 firearms last year playing with that stuff... I don't have the budget nor the desire to loose an eye playing with that crap...

Rikkie

I'm not familiar with the powders available in RSA but it sounds like the factory did exactly what would have been a better idea than duplexing. That is, blending powders. Blending S335 and S365 may have produced the equivilent of S355. Blending powders is a routine procedure with some very good benchrest shooters here in the USA, assuming YOU KNOW WHAT YOU ARE DOING.

Ray

Every day I pray to the Lord not to die at the hand of poor judgement. Just a good way to get your face taken off. There is NO justification for duplex loads. No matter the game, safety is paramount.

quote:

Originally posted by duikerman:
It is claimed that this prevents hangfires in large cases.

I think this applies to VERY large cases of calibers like 120 mm or so, have to check my Rheinmtall manual.

I've never toyed with duplex loads, because there is no need to, we have an excellent choice of powders today, almost too many to choose from.

PO Ackley was an ardent experimentor, and his works are wonderful for a historic insight as to what was at the time believed to be the best way to achieve peak performance.

That said, if you can't find a cartridge size and powder that meets your needs today, you are way off the deep end.

I used to do it, a 50:50 mix of S365 and S335, to give me an IMR4064 equivalent so I could effectively push a 69gr BTHP at 3300fps. It worked extremely well but it was a real PITA.


Then Somchem woke up and developed S355, and that was an end to the duplexing.

American reloaders have no need to do it, but us here is SA had to if we wanted to get good performance. Just too many gaps in the powder line up.

I do remember getting royally blasted right here for even raising the subject.


Pete

If you want power from a 454 Casull, H110 will do it.

If you want to blow up a gun, AA#5 will do it.

Your canister powders are already blended from bulk powders.

duplex loads are for CANNONS and battelship guns... today, if you can't get it done with the RIGHT powder, or a little dacron above it, in 130+gr capacity cases, then you need to buy quickload and start from there.

h110 or w296 for big pistols,

jeffe

I duplex loads using slow powders, 860 and 870, using three grains as 3031 as the duplexing powder on the primer. Use a FULL case so they don't mix. THe 3031 bumps up the pressure just enough to reduce the unburnt powder in the barrel. Esp. 860 duplexed loads have been the most accurate cast bullet (and jacketed) loads I've tried in my 30-06, 308 8mm, 376 Steyr and several other rifles. This isn't withcraft and is the perfect example of people spouting off who clearly know nothing of what they are writing about.

Several years ago a popular forum called TalkSHOOTERS failed. THe cast bullet forum members came here to AR. THey began discussing duplexing and were immediately assaulted like they were witches out of the 1600s. They left starting http://castboolits.gunloads.com/index.php THey have thousands of hits a day. TRy counting the hits on the AR cast bullet forum in comparison. Go on over to the castboolit forum, you may learn something.

TED

An explanation of duplexing black powder cartridge loads from bpcr.net. THey clearly say it can be dangerous.


The BP Cartridge Rifle Reloading Guide



http://www.bpcr.net/site_docs-results_schedules/documen...ading_dick_trenk.htm



Basically, a duplex load involves putting a small amount of smokeless powder into the case first, then the black powder is placed on top of the smokeless powder.

No wad or material is used to separate the two powders.

The BP is compressed in your usual manner and the over powder wad (if used) installed, then the bullet is seated on the wad in a normal manner.

The smokeless powder selected must be of a fairly slow burning rate, thus a fast burning pistol powder would produce dangerous pressures with possible damage or injury.

While the Canadian rules allow up to 25% of the black powder charge "weight" to be replaced with an equal weight of smokeless powder, this is in the opinion of most US shooters to be both excessive and highly dangerous in even modern made guns.

Experience has shown that Alliant Reloader 7 or IMR 3031 or IMR 4759 powder used in place of 5% to 10 % of the original BP charge weight delivers a large speed increase as well as a very clean barrel condition.

This author has used up to 5% of IMR 4759 with good results and pressures remained in a safe range. I would not use more than 5% because a stronger pressure is simply not needed.

The ASSRA shooters seem to prefer the IMR 4759 powder.

Other powders which have a similar or slower burning rate may also be tried in small percentages and such loads are to always be developed with strict attention paid to pressure indications during firing tests.

The above mentioned Accurate Arms book will provide that firm’s smokeless powder recommendations and other powder firms can be contacted for their suggestions for use of their brands of smokeless powders.

Remember...remove the same percent of weight from the original BP charge and replace it with the same weight of the smokeless powder.

Example of a 10% duplex charge: Original BP charge weighed 70.0 grains. Ten percent would be 7.0 grains.

Therefore the final loading would be 7.0 grains of a proper smokeless powder plus 70.0 minus 7.0 equals 63.0 grains of black powder. The total of both powders comes back up to the original 70.0 grains.

From the very beginning of smokeless powder, the shooters started to add smokeless to their BP loads. They obtained faster muzzle velocities and cleaner barrels just as we get today.

Because accurate pressure testing cannot be done by ordinary shooters, you simply have no way to know the amount of internal chamber pressure and the time lapse in which it occurs.

Such costly and highly technical measurement equipment is found at gun and powder manufacturers, not at home loading benches.

To my knowledge, no powder manufacturer actually publishes any duplex loading suggestions because of the obvious dangers involved. I advise you to consult other shooters who have developed a safe duplex load for your caliber and bullet weight.

This sharing of duplex information is common on the several internet "chat boards" and dedicated BPCR "message boards."

The Pedersoli company does not officially recommend or authorize the use of any duplex loading due to the impossibility of knowing just what pressure any duplex load would develop. If you decide to shoot duplex you do so at your own risk

Ray (Cheechako),

Yes - the factory did EXACTLY what reloaders had been doing for some time, when they developed S355. Is that not precisely the benefit (for all) derived from the (mindless?) few who would not settle for second best? I mean - had early 'duplexers' not been digging for what was to become S355, would it have come about at all?

You guys have good reason to be grateful for the plethora of goodies you have available on your doorstep.

Thanks for the information.

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Tact is for people that are not witty enough to use sarcasm.