Duplex


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Vacek
August 2, 2010, 11:57 AM
Please correct me if I am wrong but didn't both Elmer Keith and Philipe Sharpe experiment with duplex loads with significant success?

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MEHavey
August 2, 2010, 12:43 PM
See
http://www.saubier.com/forum/showthread.php?t=2730

Msg#4

It seems that things depend on what "duplex" means.

rbernie
August 2, 2010, 01:09 PM
I've been around energetic materials research and testing since I was old enough to walk and read, and I've read about the results of many a test shot that went awry because the compounds behaved in unexpected ways.

As far as I know, no modern powder manufacturer or testing lab advocates nor provides load data for commercial loads that mix two or more powders. That right there says all that should need to be said, at least to me.

R.Clem
August 2, 2010, 01:40 PM
A book by Wolf Publishing titled "Gibbs' cartridges and Front Loading Techniques" copyrighted 1991, gives very specific information about using tubes in civilian cartridges.
I have experimented with this technique in a .300 Win. Mag. with some very promising results, but, the process is very time consuming and requires some machined tools for the execution. I do not believe the average handloader/reloader ever has any reason to use these techniques, only those who have the time, money and desire to safely experiment should even consider this.
The book also contains very interesting information if you are into experimenting with different techniques for handloading.
I do warn those who are interested in using real "duplex loads", do not do this with out the use of tubes in the case to start the ignition at the front of the charge. If you use a fast burning powder and slower powder over the top or vice versa, you are asking to be injured or killed.
If you load the fast burning powder at the base of the case, it is the first to ignite and there fore the pressure has gone out of sight before the slower powder completes it's ignition and increases the pressure even more, BOOM. If you load the fast burning powder over the slow burning powder, the same happens, but it is a little less violent, like that really matters when your firearm has just blown up in your face and killed or injured you or bystanders.
Just read this thread, which has been "Closed": http://www.thehighroad.org/showthread.php?t=536439
This fellow got away with this for now, but without pressure testing he should refrain from this practice and use earplugs to fill in the left over space in the case.

Ray

SlamFire1
August 2, 2010, 02:15 PM
I also suspect they blew up a number of guns in the process.

There is absolutely no need to use duplex loads with modern smokeless gunpowders.

R.W.Dale
August 2, 2010, 02:57 PM
With the veritable multitude of propellants we have available in every imaginable burn rate what EXACTLY do you expect a duplex load to do better?

Vacek
August 2, 2010, 08:05 PM
Boys don't get me wrong. I am not advocating anything. Just that I had read that some work had been done on duplex loads.

If indeed the work had been done and by some significant persons to handloading then; they at that time must have assumed they could improve a load.

There always has been a bell curve when it comes to reloading from the far far left tail saying that reloading should not ever be done by a lay person to the far right where people experiment and in doing so assume the risk. In the final analysis hasn't the American way been a tendency of some to push the envelope whether its a family moving west to a wilderness to going to the moon.

I don't necessarily always agree, but neither will I castigate.

Greg Mercurio
August 2, 2010, 08:17 PM
One would hope that the right end of the bell curve has lots of room on private land and a remote trigger manipulation capability to fire and possibly contain the results.

Having spent a good portion of my career in energetics, the use of data acquisition would be well advised. Pressure transducers and a data logger will tell you what's going on in the chamber over time. Big P/ little T is not good for biologicals.

And I'm in total agreement of the left end, the range is populated every Sunday afternoon with people who probably should not even own firearms, much less reload. :D

rbernie
August 2, 2010, 08:36 PM
I don't necessarily always agree, but neither will I castigate.That's a great philosophy in general (one with which I wholeheartedly concur), but sadly it just doesn't translate well to certain topics. Energetic materials is one of those topics, IMO.

I spent some portion of my life reading cutting edge research papers about deflagration-to-detonation transition (DDT) studies (http://en.wikipedia.org/wiki/Deflagration_to_detonation_transition). One of the things that I learned from that background is the UNPREDICTABLE nature of these sorts of things. In many ways, we are still meddling with powers that we cannot possibly comprehend (to steal a quote). Boyles and Charles and pV=nRT and linear flame front progression through a substrate and all those other notions from junior high organic chem sound great on paper but do not stand up to the realities of actual combustion within an irregular pressure vessel.

You just don't mess around with this stuff. Linear extrapolations are usually safe but can go very wrong if some of the basic parameters are overlooked. All else is folly outside of a very controlled lab setting.

BTDT.

ranger335v
August 2, 2010, 09:36 PM
Keith and some others tried to make duplex charges work, some with front ignition, but they all abandoned the idea. They blew up some good guns too. Don't know as Sharpe ever fooled with it. No one I know of was silly enough to attempt any "blended" charges tho. Both of those bad ideas get floated occasionally by some young feller having a brain fart and believing he's come up with a bold new concept.

Oyeboten
August 3, 2010, 12:20 AM
I have experimented a little with Black Powder and Smokeless 'DUPLEX' Loads for .38 Special.


I am not yet ready to discuss in detail though, but, at some point I likely will start a Thread for it.


Seems to work splendidly, and, along entirely predictable lines of what I expected in laying out my Graphs before hand.

Because there are so many variables, I believe most people became closed minded or rejecting of the idea superficially, and or impatient in rejecting it also in not having any interest to think about it in detail, especially for Hand Gun Cartridge.

It is a subject which will tend to get emotional responses disfavoring it...with zero interest in assaying crucial details.

Hence, whoever is doing it successfully, is not likely to bother saying anything about it.

Venado
August 3, 2010, 11:25 AM
I could not sleep at all last night because of this thread. "It is a subject which will tend to get emotional responses disfavoring it". I am not a person to encourage everyone to go out and experiment with such a technique. Oyeboten, I am sure there are many out there that load in such a way, but are afraid of the ridicule if they were to admit it. I do not use duplex loads, triplex is much better.

rbernie
August 3, 2010, 11:28 AM
It is a subject which will tend to get emotional responses disfavoring it...with zero interest in assaying crucial details.

Hence, whoever is doing it successfully, is not likely to bother saying anything about it.Waitaminute - that's simply not fair. Let's try this again....

It's OK for you to try whatever you want, so long as you're alone in your basement or garage and alone at the range. It's OK for you to hand out your email information to folk and suggest that they contact you if they want access to your data and your procedures. Nobody here probably cares too much about any of that. It's quite another thing to use somebody elses' private forum to advertise handloading procedures and recipes that are not backed by any formal lab work and for which there is ZERO support within the reloading consumables industry.

You are not providing legal coverage for the forum, and you are not taking legal and financial responsibility when somebody tries to duplicate your work and causes harm to themselves or others. That means that you have little right to stand up and cast aspersions at others when they shy away from endorsing your efforts and/or providing you a venue within which you can publish your efforts.

Do what you want. Just don't stand up and demand the right to use THR as the means by which you encourage others to duplicate your efforts.

I am not yet ready to discuss in detail though, but, at some point I likely will start a Thread for it.You might wanna check with Johnny before you do; this is his subforum and he likely will take a dim view of you starting a thread on the subject when he clearly closed down the last one as inappropriate for this venue.

Johnny Guest
August 3, 2010, 02:07 PM
Thank you, rbernie, for stating the case very clearly. You've said it so well that I can only add a couple of comments and some rather lengthy observations.

Vacek wrote: " . . . didn't both Elmer Keith and Philipe Sharpe experiment with duplex loads with significant success?" Much depends on the definition of "significant success." Short answer: NO. Not to the point where results were safe, repeatable, and practical for commercial or individual handloading.

Oyeboten , do you feel that you've been smitten by some celestial revelation, giving unto you a pattern for success not granted to our forbears?

Please, go to the top of this or any other page on THR, click the Search button, then Go Advanced, select Handloading and Reloading area, and enter search terms "Duplex loads" and "Blended powders." Then go over to thefiringline.com and do exactly the same. Save the results you get. Look up the links and read them. You'll likely find that there is little new under the sun. You'll also find that the responsible and reasonable members of both boards universally shy away from these extremely hazardous experiments.

These suggestions are made only to give you some valid background information. The topics discussed might well save you some false starts on your road to experimental enlightenment.

A little background might be of interest. When I started my career as a peace officer in the mid-1960s, I was already a shooting enthusiast. The policy manual at my first agency, Tarrant County Sheriff's Office in Fort Worth, specified little about firearms. Deputies furnished their own sidearms, "Colt or Smith & Wesson, in caliber .38 or .357, with four-inch barrel." Deputies with S&W Magnums (pre-Model 27 or Model 27) with 3.5-inch tubes were allowed variances.

Nothing was specified as to ammunition. Commonly available ammo for .38 Special was 158 gr. LRN rated at ~ 860 fps and 148 gr. wadcutter target loads at about 730. If lucky, you could scounge some air force ammo, 130 FMJRN at maybe 800 fps. Rarely, one found Remington High Speed (.38/44) loads, the same 158 LRN at about 1080 fps. Available .357 loads were even more limited: Remington and Winchester both had a short-nosed (Thompson design?) LSWC 158 that leaded terribly. The Win was copper plated, the Rem plain grey lead. Remington sold their .357 High Speed, a flat-nose 158 JSP witrh a FEARSOME muzzle blast and very stout recoil, even in my heavy Highway Patrolman (pre-model 28) revolver. Still listed was a metal piercing load, 150 conical flat tip FMJ high speed, in both .38 Spl and .357, but I never saw a box on the shelves.

Within two years, Lee Jurras of Super Vel brought out his then-revolutionary light bullet high speed ammo. The same 110 JHP and 112 gr JSP bullets were loaded in both .38 Spl and .357, at about 1150 and 1450 fps, respectively. (At least, per the ads. ;) )

During that time, I read every scrap of writing I could locate concerning enhanced performance .38 and .357 ammunition. Elmer Keith held godlike status, and Skeeter Skelton was his prophet in the Texas Panhandle. Jurras and George Nonte pioneered handgun hunting as something other than targets-of-opportunity activity. Keith and Skelton liked heavy bullets pushed pretty swiftly with stout charges of medium- to fast-burning powder. Jurras wanted lighter bullets at screamingly fast velocities. Major Nonte kinda went to and fro. Common threads: all these guys, and several others, were doing everything in their power to upgrade the ammunition available for holster guns, be they carried for sport, peace officering, or perfsonal defense.

Those guys had the ear of the powers-that-were in the firearms and ammunition industry. They were often beta testers for cutting edge developments in guns 'n ammo. They led the way to development and acceptance of the .44 Magnum, the .41 Magnum, and the developing field of handgun bullet designs. And, yes, they occasionally reviewed ideas for some pretty exotic stuff - - Forward ignition using flash tubes, a la artillery shells, and, especially with the advent of Dick Casull, multiplex powder loadings. It may be of interest to note that Casull, an early booster, soon backed away, FAR away, from multiplex loadings

Now, all the foregoing is merely to indicate that a lot of well-advanced individuals have been out there before us. True innovations are often wonderful. It may be a touch presumptious, though, to ignore those who went before us, frequently already having ploughed the gound we tread today.

You seem apprehensive that you'll be quashed for presenting your revolutionary ideas. Given the background of Duplex powder threads here on THR, rbernie and I have some standing to judge the validity and safety of posting certain load types. Start your thread if you please, stating your underlying thoughts and theories. DO NOT, though, publically post specific loads without prior approval.

Best
Johnny

Clark
August 3, 2010, 02:15 PM
There are duplex and triplex loads for the 454 magnum on page 521 and 522 of Ackley's volume 1 handbook for shooters and reloaders 1962.

ranger335v
August 3, 2010, 06:17 PM
"There are duplex and triplex loads for the 454 magnum on page 521 and 522 of Ackley's volume 1 handbook for shooters and reloaders 1962."

Yes...but...there are (1) no details and (2) there is no recommendation to do it.

Fact is, the very high speeds were obtained with very high pressures and that, of course, at great risk snd often in specially made cylinders.

All of that was done 50 and more years ago. When affordable chronographs became widely available it was soon learned that the same speeds were safely obtainable with a single powder. Today we have a much wider variety of powders so duplex/triplex charges make even less sense than they did back then.

Venado
August 3, 2010, 10:28 PM
"it was soon learned that the same speeds were safely obtainable with a single powder. Today we have a much wider variety of powders so duplex/triplex charges make even less sense than they did back then." I don't know how to say this, don't mean to be a smart a, but would you like to wager on that?

Vacek
August 3, 2010, 11:32 PM
I did some interesting reading tonight from Sharpes book. His discussion of duplex loading was interesting in that they did find improved performance with duplex loads but were unable to manufacture the cartridge where the two powders would remain unmixed. Unmixed they got good results but any kind of vibration, movement, transportation would result in powder mixing and according to Sharpe even some pressure guns blew up. One of his statements or a quote of another that he wrote in that chapter was they believed that 50 years down the road the problem of keeping the powders from mixing would still not be solved. He was right.

Venado
August 4, 2010, 10:01 AM
Vacek: that is strange, maybe the 50 years is up. With the powders we have now, it is a different story. Infact, my 9mm load is so well compressed that if you pull the bullet, you have to break up the pellet that the powder has formed.

ranger335v
August 4, 2010, 06:24 PM
"duplex/triplex charges make even less sense than they did back then."

"I don't know how to say this, don't mean to be a smart a, but would you like to wager on that?"

I know how to say it: Yes.


"Infact, my 9mm load is so well compressed that if you pull the bullet, you have to break up the pellet that the powder has formed."

Do you really think your 9mm compacted powder pellet retains it's distinct layers after ignition? I don't.... :) !

Venado
August 4, 2010, 06:40 PM
So, I guess since you said yes, you have loads that with conventional loading, will out perform mine. So where do we meet, and how much are you wagering?

ranger335v
August 5, 2010, 11:14 AM
Don't be silly. But, if you want to come to the mountains of N.C. you are welcome to do so and you can try to prove me wrong with a chronograph on my private range. I don't normally bother with the little krunchen-ticker cartridge, it's only a .38 Special +P with light for caliber bullets so we would have to use your pistol. But I do have the dies and components.

I really don't care what you think your magic loads do and you haven't given any velocities. But, I'm certain I (and most anyone else) could easily match any duplex velocity you put together at standard pressures and do it with conventional powder charges.

R.W.Dale
August 5, 2010, 01:00 PM
So, I guess since you said yes, you have loads that with conventional loading, will out perform mine. So where do we meet, and how much are you wagering?
If you're getting higher velocities with duplex loads compared to std loads it's because you're running higher PRESSURES PERIOD END OF STORY

So what are your pressures running in PSI? As cutting edge of a handloader as you are I assume you have a pressure trace system? Or are you merely just another brass guesser?


BTW You can ramp up pressures and thus velocity with overcharges of single propellants just fine without inducing another element of unpredictability

Venado
August 5, 2010, 02:10 PM
Krochus: Do you have a pressure trace system that you can test .45 acp with. I am not too far from you. Would love to come visit.

Vacek
August 9, 2010, 10:51 PM
Man, this is getting interesting from a historical viewpoint. I was reading "Volume 1 - Reloading Information" from the American Rifleman, published in 1951. I love these old books....Shouldn't say old as I was born in 52.

On page 77 tey discuss a load for a gas checked cast bullet for the 30-06 by a Paul G. Mansfield, New Boston N.H. I quote, "He gets good results using a booster charge of pistol powder along with a light load of slower-burning powder. One favorite combination is 4.0 grains of Pistol Powder No. 5 and 19.0 grains of 4198". The combination tested for velocity was 20.8 grains. These mixed powder charges are intended to promote powder combustion and are safe at such low pressure levels."

Seems like some of the boys were experimenting back in the day.

In the next paragraph they discuss zinc-alloy cast boolits.....Hmmmmmm

JT-AR-MG42
August 10, 2010, 06:57 AM
Oyeboten,

You probably already know duplexing black - 5% - has been done since smokeless has been around. Slight increase in velocity, but the obvious reason is for a cleaner bore between shots. You also end up with less case fouling in the cases of cartridge guns.

Competitions do not allow the duplex loads to level the field. That is not to say that that duplex gives an accuracy advantage at all. They are just cleaner to shoot. One can easily spot duplex by the lack of volume of sparks 'falling' from the barrel upon firing.

Most frontloaders just mix it in prepared charges. With your cartridge gun, try some mixed, smokeless to the rear, and smokeless to the front. I have. Run them over your chrono and you'll see no difference. The primer lights the black first regardless of where the smokeless is. It just makes for a cleaner shooting load. The smokeless is pushing fouling out of the case and bore. Putting it in first is really only a simpler method of controlling consistent powder weights.

Venado mentions triplex. Is that with black? I've never heard of it in blackpowder guns.

A friend and I messed with a Shiloh Sharps .50 and smokeless/smokeless duplex. Fired cases extracted normally and showed no pressure or increased head expansion when measured. We quit because the recoil - more than 45 degrees - was just too much of a fun thing, not because of any concerns over the gun or load.

I do not recommend anything to anybody, JT

Vacek
August 10, 2010, 07:35 PM
Yes, it seems like in the past there was signifigant R&D going on. I read Phil Sharpe's encyclopedic book and reloading was pretty much figured out a generation ago. The tools have gotten more convenient, the components, especially the powder when it comes to temperature seem better, but as they say....Ain't nuttin, new under the sun.:what:

sonier
August 10, 2010, 07:54 PM
Tinkering around the idea of duplex loads sounds fun, but i would first grab a cheap "disposable" rifle such as a old beat up mosin nagant. I would also set up a safe firing range that can be controlled from a distance. Such as a hydraulic trigger or old string trick. Id also want to be hidden from shrapnel so a old concrete bunker, or wall would work. The last thing i would want would have to be a way of testing pressure. Maybe one day here soon i might give duplex loads a try if i save some coin and try a few things.

ranger335v
August 10, 2010, 10:10 PM
"I read Phil Sharpe's encyclopedic book and reloading was pretty much figured out a generation ago. The tools have gotten more convenient, ..."

It was much of the work of that generation that drove the development in reloading tools, components and even our firearms. Many of todays shooters seem to think they invented all the stuff they use and the "old guys" weren't nearly as smart as shooters are now! Huh?

Oyeboten
August 11, 2010, 03:28 AM
Results in both my 'Duplex' Loadings for .38 Special, and, in people's reactions to it even being mentioned at all, both fall upon the exact anticipations I had formed.


Why may this not be a rational matter?

Why insist to interpolate and project into my mention, things I never said, claimed, or had for motive?


The matter seems to invite mostly very messy and emotional reactions, instead of rational interest...

This seems sad to me.


I think the topic itself is in fact more 'dangerous' ( to even mention, let alone, discuss! ) than the actual practice ever was.


Nor is the practice 'dangerous' ( or any more 'dangerous' than using any propellent for that matter ) if rationally thought out, and rationally managed.


Endless examples of doing anything badly or wrongly where bad results follow, can be found for anything and everything in Life.




Impetuousity or transpositions or other errors of technicality or judgement, can or will occasion problems or disappointment in any endevor, and re-Loading is no exception.


I have not recommended anything to anyone about 'Duplex' Loadings, and I have not offered anyone any 'recipes' on or off list.


Sheeeesh!


You need a Snow Shovel here sometimes to clear the BS people can deposit.


Anyway...


Oye...

Oyeboten
August 11, 2010, 03:54 AM
Hi JT-MR-MG42,


You'd mentioned -


Oyeboten,

You probably already know duplexing black - 5% - has been done since smokeless has been around. Slight increase in velocity, but the obvious reason is for a cleaner bore between shots. You also end up with less case fouling in the cases of cartridge guns.


There were and are other reasons, and, other proportions, which at one time were held in favor for Black Powder Rifles, and, for all we know, Pistols also.


Their reason at the time, was for not only a little less fouling, but, for a little more FPS and or for wishing to control the rate of acceleration.



Competitions do not allow the duplex loads to level the field. That is not to say that that duplex gives an accuracy advantage at all. They are just cleaner to shoot. One can easily spot duplex by the lack of volume of sparks 'falling' from the barrel upon firing.


This would depend on the Powder, and the proportion...as for whether anyone would 'see' anything different, or even hear anything different.



Most frontloaders just mix it in prepared charges. With your cartridge gun, try some mixed, smokeless to the rear, and smokeless to the front. I have. Run them over your chrono and you'll see no difference. The primer lights the black first regardless of where the smokeless is. It just makes for a cleaner shooting load. The smokeless is pushing fouling out of the case and bore. Putting it in first is really only a simpler method of controlling consistent powder weights.


I have already done the experiments I had in mind.

But, I may do some more also.

The differences shown with the Chronograph, were in keeping with the anticipations I had outlined in advance...and of course, showed FPS higher than BP alone.



Venado mentions triplex. Is that with black? I've never heard of it in blackpowder guns.



Triplex exists as one more method...and, as with all of this, the powders used, and their proportions and sequence and so on, are important, if not critical.



A friend and I messed with a Shiloh Sharps .50 and smokeless/smokeless duplex. Fired cases extracted normally and showed no pressure or increased head expansion when measured. We quit because the recoil - more than 45 degrees - was just too much of a fun thing, not because of any concerns over the gun or load.

I do not recommend anything to anybody, JT



My only interest so far, has been in loading Black Powder Revolver Cartridges, and, also loading with '777' or other bulky BP stand ins, keeping them in what I believe are conservative pressures, and, seeing what variations on that theme I could explore.

Although I did also take a little deteur to load some Smokeless .45 Colt Cartridges, with 'Unique', and found satisfaction and fun with that.


Black Powder Revolver Cartridges or so called BP '
substitutes' are what I am interested in primarily for now.

And, 'Duplex' variations on the theme, with BP, have been interesting to experiment with.

I kept my experiments conservative, and careful, and I had no disappointment or regret.


However, especially in the absense of details or ways of verifying pressures realized in anyone's particular conditions, I am certainly not recommending or hinting as if recommending, that anyone jump into attempting any kind of 'Duplex' Loadings of any sort.

This is an area where there is close to no published data, and since there are many ways to do it, there are also many ways to make an error of judgement which could result in a ruptured or even catastrophically exploded Gun, and possible injury to the Shooter or to bystanders.


'Duplex' Loadings based on BP interest me because it seems interesting to me.


It is not any more complex than that.


I have no fouling issues anyway, using Home-Made Lube Wafers, so reduced fouling is not a motive or care which underlay my interest in 'Duplex' Charges.

sonier
August 11, 2010, 03:31 PM
Hi JT-MR-MG42,



'Duplex' Loadings based on BP interest me because it seems interesting to me.


It is not any more complex than that.



That is a good reason in my opinion

Ky Larry
August 11, 2010, 09:04 PM
If there is an advanage to duplex loads, why aren't any of the big boys (Rem,Win,Fed,etc) offering them. They have all the smart people and all the test equipment. Just curious.

Venado
August 11, 2010, 10:33 PM
How do you know none of the big boys don't do it? If a company did do it, they would not advertise it, because they would have the advantage over their competitors. A stratified load has less muzzle flash, more velocity, and less pressure than a comparable velocity regular load. I have been using stratified loads for 17 years, and would not go back.

Oyeboten
August 12, 2010, 12:32 AM
Hi Venado,



The phrase 'Stratified Load' is a very nice choice of words..!


I have heard various wise heads of reloading mention their opinion that 'Buffalo Bore' for one, almost certainly uses a proprietary combination of Powders in attaining their celebrated FPS while staying within S.A.A.M.I. pressure peramiters.

Venado
August 13, 2010, 09:37 AM
Oyeboten, if you will look at my post 'muzzle flash', you will see the proof of what a stratified vs. normal loading will do as far as utilizing your powder charge.

Oyeboten
August 13, 2010, 01:57 PM
Hi Venado,



Where would I find your 'Muzzle Flash' Post?



Anyway...some of my brooding has indeed been about rate of conflagration, elastic rebound or other behavior of the Gasses, duration of peak pressure and when it is reached...

These being in a context always of course, of Bullet Weight and kind, Barrel Length, and diameter of Bullet in relation to Bore.

Reading various incidental things, including occasions of how overly 'light loads' for paper Target sometimes were said to result in a Bullet not even leaving the Barrel ( Pistol ), Loading Density issues when germain to pressure potentials of given Propellents...on and on...

Wondering about these behaviors...

'Stratified' definitely sounds interesting...and or as it may be arranged for any particular Cartridge of course.

Venado
August 13, 2010, 05:25 PM
Hi Oyeboten, do a search using 'muzzle flash' as the topic, it is down the first page. Or do a search for posts by venado.

Oyeboten
August 14, 2010, 01:04 AM
Thanks Venado,


Found it -


http://www.thehighroad.org/showthread.php?t=538268&highlight=Muzzle+Flash


Can you elaborate a little more without compromising discretion?

Venado
August 14, 2010, 11:50 AM
Oyeboten, The flash you were referring to is a stratified load (triplex). I use to use duplex, but found that a triplex load utilizes the powder better, giving more velocity, and less flash. The main powder charge is a powder known for its flash, and it is so slow that it won't even cycle the gun without the pre and post charge. This method is much safer than people trying to get more power out of a standard load by adding powder. I am buying pressure testing equipment next month, and then I will be able to show what is happening.

Tom S.
August 14, 2010, 12:54 PM
WARNING: Thread Hi-jack in progress!

I have Phil Sharpe's handloading book but don't remember anything in it about duplex loads. Can someone tell me where they read about it? :confused:

We now return you to the regular thread. :)

Oyeboten
August 14, 2010, 04:26 PM
Hi Venado,



Very interesting.


My own broodings which preceded my experiments in loading some Black Powder Based 'Duplex' Charges, set out to see how much a given amount of the second powder would effect the FPS, while lessening the BP Charge to that same weight as that of the added 2nd Powder.


I only added very small amounts of a 2nd Powder, and, I thoroughly mixed the two, rather than to have the 2nd one concentrated in any place within the Cartridge.

Results fell upon entirely even and arithmatically progressive lines of increase for the FPS, while, I felt confident, my Pressures remained well within the lower or mid 'SAAMI' range for .38 Special.

I did not take this especially far, having only tried lower end combinations I felt were conservative.

Recoil and Report seemed to co-respond to the incriments of addition, also, if somewhat subtley.

Too bad there are not one-time-use Cartridge Cases, designed to somehow register pressures!


That would sure be handy.


My Test Gun for this was a 3 inch Barrel S&W Model 10.


Still have not found my notes though.


Stratified 'Triplex' Charges of Smokeless propellants of course is a different matter, if having some things on common.


My BP Chares were compressed, thus lending very little free or available Air to the small Smokeless component, which I figured would be alright, since the Smokeless propellant was limited to only some very small amounts, and would be deprived of any ambient Air anyway by the conflagration of the BP.


I was able to work out the increase in FPS for each .5 Grain increase of the Smokeless, which I think turned out to be about like what an added Inch of Barrel increments would have done, with plain BP Charges.


This was very interesting to me...and, to some extent, was also about how an enhanced Black Powder Charge, for a shorter Barrel, could provide Ballistics similar to what a longer or long Barrel would deliver on plain BP...while probably not getting very far into the mid or upper teens of PSI ( in my imagination anyway, since I have no real way of checking).


I imagine quite a few people did this very thing, with whatever care, methodology, or naivete, back when the Smokeless Propellants were still fairly new and limited in variety.

rbernie
August 14, 2010, 04:29 PM
Time to take this two-way dialog to PMs, please. :)

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