Maybe this has been covered before. Many years ago when I was young and thought I knew everything about reloading an old man I was working with asked me if I had tried loading any "duplex" loads. Having never heard of it I asked him to explain. According to him it was common to load a rifle case with a small bit of fast powder next to the primer then top with a slow burner. Some even loaded three different powders. He said the idea was to get a better burn started on the slow powders and the pressure waves canceled out excessive pressure. Much higher velocities were claimed. I'M NOT ADVOCATING TRYING THIS! I have never tried this and it sounds very dangerous. Maybe the old timer was jerking my chain but perhaps some of you know something about this?

The first blown up Ruger Superblackhawk, I ever saw, was using tri-plex loads.

They are still being used by a few of the more exclusive load shops. Hopefully with a lot more knowledge than when your friend was loading.
And too, today we have a much wider range of powders that are much more consistant so we don't need to resort to that sort of daring.

yes some use them in muzzle loaders clint

larkin

A search will turn up a lot of threads on duplex loads, on this and other shooting forums.

To say that duplex loads were "common" is a bit of a stretch. It's also a stretch to say that any real benefits were ever realized.

Given todays powders and various case sizes and configurations I can't see where anyone would want to try it again but the idea seems to pop up every few years as new shooters forget the past.

JMHO

Ray

Fortunately for me I missed the heyday of duplex loading by about 15 years or so, or else I might have "strained" more stuff than I already had!

IMHO (which is just an opinion since I wasn't there) is that it was brought about by a limited choice in powders (compare the choice of powder in an old catalog to all the current selections!) and also a huge amount of dirt cheap mil surplus powders designed for 30-06 and 50 bmg.

As mentioned, some people got pretty spectacular performance numbers but combining powders is always going to be an inexact science, whether you blend them or load them in a particular order.

And again, that was then and this is now. It can be argued it made sense at the time but there is certainly no call nowadays to do this with all the choices available to the reloader.

The only time I've ever loaded duplex loads it was using a small ammount (3gr) of bullseye under a compressed charge of black powder.

The idea behind this was to decrease the ammount of fouling.

The results were not all I'd hoped, but if I load any more black powder loads in cartridge arms I'll do it again, because
there was a noticable reduction in fouling.

Particularly in the fired cartridge cases.

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how do you keep the fast burning powder next to the primer?

heavy compressed load and gentle handling

Loading duplex loads at home will get you a partition between the right and left lobes of the brain............

If you look on our own forums reloading page under the 700 Nitro Express you'll find that they used 2 grains of Bullseye to halt the occurance of hang fires... Not to say this is a practice I would undertake but it has been done before...

KSTEPHENS, I hear ya, how do you keep the fast burners next to the primer ...

Ken....

I believe in the early days of developing the 454 Casull triplex loads were used to get the desired speeds. Then along came WW296 & H110 and that nonsence stopped.

I have experimented quite a bit with duplex loading. Even when you think you know what you are doing and approach max. pressures in what you think is a safe manner it can bite you in the ass.

A lot of this work was done with H 870, 5010, and 5020, but not exclusively. Gradually increasing the faster powder everything might appear to be placid.HOWEVER, once you get up to a temperature and pressure where the slower powder really starts to burn you find you got too much of it in the case and you notice yourself doing Clark type of testing ( brazed cases to bolt faces,Severe action set back,and some other nasty stuff.

Haven't done any of that in a while now. roger

A word of caution Duplex loading is BEST left to Factory people !. They have the Pressure barrels for development . I've used them in Shotgun loads with NO problems but will not attempt them for Center Fire Cartridge loading , just to dangerous . Powder can be mixed in an unpredictable off set . I Still got 8 fingers 2 thumbs both eyes and more hair than a grizzly , after 40 Years of reloading . I'll keep banking on that record !!.

FYI Remington & Winchester ( Shotgun Shells ) both use Duplex loads in certain mainstream offerings .

Shoot Straight Know Your Target . ...

many moons ago some guys used to duplex a small amount of 4895 under a casefull of 4831 in things like a 244 trying to get better ignition and more velocity. don't think it worked to well.

What Alan said. I too have tried duplexing BP in my .45-70 Sharps. As I recall, I went from about 2 grs. of SR-4759 (I think) up to about 7grs. There was a noticeable increase in recoil so I stopped. As Alan said, it was used in an attempt to reduce BP fouling.
I believe that Elmer Keith expounds on this subject quite a bit in his book "Hell, I was There".
Bear in Fairbanks

quote:

Originally posted by KSTEPHENS:
how do you keep the fast burning powder next to the primer?

when the fast (bullseye) powder is loaded first
then a case filling charge of FFg or FFFg loaded on top of it and COMPRESSED where exactly is the bullseye supposed to go?

4grains of RedDot under a 357mag case full of FFg topped with a 158grain cast (GC) semi-wadcutter is hardly what I'd consider dangerous in ANY 357 firearm.

In terms of real pressure the back powder is nearly irrelevant and the 20-ish grains of it can essentially be treated as additional projectile weight, but it makes an impressive cloud of smoke and that distinctive blackpowder "CRUMP" sound...

Yes, there was a bit more recoil from doing this, as compared to black powder only loads but nothing like the recoil from full power smokeless loads.

Ditto for a 44Mag with somewhat more black powder.

The other very real problem I had and was trying to eliminate was that if nickel plated cases were used and not washed IMMEDIATLY they would disintegrate instead of going into the sizing die...

I didn't eliminate that problem either.

quote:

Originally posted by Dr.K:FYI Remington & Winchester ( Shotgun Shells ) both use Duplex loads in certain mainstream offerings .

Shoot Straight Know Your Target . ...

The Remington "duplex" shotgun loads mix SHOT sized, not propellant.

AD

I've used 2400 under black. Smokeless/black loads seem to burn a bit cleaner than straight black.

quote:

Originally posted by craigster:
I've used 2400 under black. Smokeless/black loads seem to burn a bit cleaner than straight black.

Hmmmm.. Now that you mention it I'm going to have to try that.

2400 or H110 is "safe" in the cartridges I use in FAR greater quantities, so 5-7grains under a pistol case full of FFg is entirely reasonable...

My problem with black powder cartridge loads is that I want the smoke but not the cleanup and the various black powder substitutes all fail to produce the smoke & smell and are generally FAR more corrosive.

Allan,

I use 7 grains of 2400 for cartridges that are in the 45-70 size range. They do burn cleaner.

Duplexing reminds me of the 'Larry the Cable Guy' joke:

What is the most common "last words" of men from down south....

" hey Fellers, watch this!..."

Didn't duplex and triplex loadings reach their peak of popularity BEFORE chronographs were readily available to the public?

P.O. Ackley "Handbook for Shooters and Reloaders Vol I" 1962:
page 521: "..Dick Casull...Colt Frontier...5 shot cylinders..special [steel].. powder charges are introduced into the case in the order given... primer pockets altered..Remington 9 1/2 primers.."
454 Magnun, 230 gr, 2 gr Unique, 25 gr 2400, 3 gr Bullseye 2000 fps
250 gr 2 gr Unique, 25 gr 2400, 2 gr Unique 1890 fps
300 gr 25 gr 2400, 2 gr Unique 1710 fps

20" barrel Model 92 Winchester rifle:
230 gr, 2 gr Unique, 25 gr 2400, 3 gr Bullseye 2315 fps
250 gr 2 gr Unique, 25 gr 2400, 2 gr Unique 2185 fps

quote:

Originally posted by jerkface11:
Didn't duplex and triplex loadings reach their peak of popularity BEFORE chronographs were readily available to the public?

yeah, back when medical cost were reasonable.

Interesting thread.

First ; years back I use to build shootable canons. The use of a small amount of fast burning did indeed yield cleaner burning.

I would be interested to hear someone's results using H-110 as a kicker in black powder fire arms. The reason being I have experienced FLAME OUTS using it in a revolver. The same ammo in my wife's 38 special rifle worked fine. It seems that 110 doesn't burn too good if the pressure and temperture aren't maintained quite high.

IMHO the duplex loading with black powder is a far different animal than duplex loading ,or triplex loading of smokeless powder.You will never get the jack rabbit jumps in pressure with the addition of just one or 2 grains of fast burning powders where the total charge is perhaps over 45 gr.. I have with smokeless powders.

Nice thread roger

#1). This is ancient practice from back when there were not alot of powders, different "kinds" / "burning rates" available to shooters/reloaders...
#2). Elmer Keith, in his writings, talks of buying a surplus Sharps with a "rotten barrel" cheap and a new barrel from Bannerman and having the barrel installed. I think this was .45/90 and he used a couple grains of a smokeless --SR4759???-- under the case full of black powder to "blow out the crud and reduce cleaning time/fun...
#3). Later, as a government employee at some arsenal--Utah??, he worked with a duplex powder load for the .50 caliber Browning machine gun. Claims he achieved an additional 200 feet per second with acceptable/normal pressures, BUT normal handling of the round mixed the powders and produced inconsistent results and dangerous pressures. Project abandoned.
#4). Rocky Gibbs, gunsmith, was an experimenter. His "Gibbs" cartridges survive. About all you can squeeze out of a .30/'06 case, but those cases, post WW II, were plentiful and CHEAP... He also worked with a process where a "primer flash tube" was screwed into the primer pocket/flash hole from inside the case to deliver the primer ignition near the front of the round. I believe he recommended about 2/3s of the way up to the base of the bullet. Into this special case with this tube plugged, he would load a fast powder first AND THEN the slow powder before seating the bullet to create a compressed charge. Obvisously, the slow powder would ignite first and get the bullet moving and only later would the fire reach the faster powder... "flatten out and maintain the pressure curve high end..." Again, rounds not meant to ride around in the glove box of anything... I read of this in a book about Mr. Gibbs by Wolf Pub, Phoenix. With todays wider selection of powders it would take much, much more work/refinement to improve on standard data and you still have the "delicateness" of the loaded round... I don't plan to try it any time soon.
#5). Then there were the fast draw shooters who had to break a ballon with the "ejecta" from their shot to stop the timer. Black powder was not reliable and they took to mixing a real fast smokeless with a real slow smokeless so at close range the hot, burning fast powder particles would pop the ballon but if you happend to be a bit farther back, then the larger, slower burning particles would still be hot enough to do the job. I think that story was in a gun Digest many, many years old...
Ancient practice now a bit obsolete. But if you must try... Check on your insurance first, please. HAPPY NEW YEAR. LUCK. Happy trails.

quote:

Originally posted by Gary Surko:
I believe in the early days of developing the 454 Casull triplex loads were used to get the desired speeds. Then along came WW296 & H110 and that nonsense stopped.

That's my recollection as well. I also recall reading that Dick Casull destroyed more than a few pistols along the way...

The very first time I heard of a duplex ;load, it was being used in caplock and single-shot Scuetzen-type black powder single-shot target rifles. The load consisted of +- 5 grains of DuPont Bulk smokeless as a priming charge, then a load of black powder on top of the smokeless, reduced by 10%-15% from a full bp load w/o the smokeless. later, others tried it, incluyding, I believe, Elmer Keith when he was working with O'Neal & Hopkins on cartridges with front ignition tubes down the middle of the cases. The first .454 Casull loading data (in the ASckley handbook) included some duplex and triplex loads.

This way of loading ammo is definitely NOT RECOMMENDED!

I didn't realize by the original post we were speaking of black Powder cartridges .

Allan ; When I tell you that Remington as well as Winchester offers Duplex loadings in some of their main stream shells , I wasn't referring to the Shot !. I do how ever acknowledge that Remington does offer Duplex Shot also . One can never reproduce factory speed and low pressures in those shells , because they are Duplex powder loaded . Powder manufactures use things which aren't available to the General Public .

Shoot Straight Know Your Target . ...

elmer keith used the term "duplex" to refer to front-ignition from a long primer tube during WWII. in a misinformation effort they said it was using two powders. he explained it in "hell I was there."

The only duplex loads I have ever used were a mix of #6 and #4 shot for turkey. Works great.

I did it in my hornet - after a lot of soul searching! I was able to propel a 58 gr projectile fast enough to stabilize using 'H4227' duplexed with 'Varget'. For a 55gr projectile, I layered the powders, 'H4227' then 'Varget' then a little more 'H4227'. The load was 7.4gr 'H4227' with 3.4gr 'Varget' totalling 11.1grs, a bit up on the usual 9gr max listed for H4227. Pressures were moderate and penetration tests showed a considerable improvement in velocity.
BUT WHAT A PAIN!
Well, that was just for fun.
Then I got some Lil'Gun and that works much better! I even get 'accuracy' with 58gr projectiles! (Made by cutting off the exposed lead tips from Hornady 60gr spire points).

quote:

Originally posted by bartsche:
Interesting thread.

I would be interested to hear someone's results using H-110 as a kicker in black powder fire arms. The reason being I have experienced FLAME OUTS using it in a revolver. The same ammo in my wife's 38 special rifle worked fine. It seems that 110 doesn't burn too good if the pressure and temperture aren't maintained quite high.

IMHO the duplex loading with black powder is a far different animal than duplex loading ,or triplex loading of smokeless powder.You will never get the jack rabbit jumps in pressure with the addition of just one or 2 grains of fast burning powders where the total charge is perhaps over 45 gr.. I have with smokeless powders.

Nice thread roger

I'll let you know, but I'll say right now that when H110 is involved in loading I reach for the Magnum primers... because in my experience it burns dirty with a Giganormous flash without a hot cap to light it up.

And yeah, sparking up black powder with a small bitof smokless to "clean things up" IS very different from real "duplex" loadings.

And on that note I remember that the original factory 454Casull loadings were supposedly duplex loads, though with what and what I have no idea...

BTW, checking my propellant inventory I am completely OUT of 2400 and H110.

So if I load up some BP/duplex cartridges I'll have to use BlueDot, which I've got 6lb of...


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