A question for the Elmer Keith buffs here

[gregintenn]

I was reading some old Keith material yesterday, where he went into pretty good detail about the Duplex load he and others developed. The premise seemed solid. Why did this never catch on?

[Muley Gil]

IIRC, at the time that this load was developed, no suitable slow powder was available.

Once 2400 came out, there was no need to use this somewhat dangerous procedure.

[Wyo]

I've used duplex loads in black powder cartridge loads. Used a small dose of IMR4198 under a big charge of FFG black in Sharps paper patched bullet loads - usually the bullet was around 500-550 grains. This gave only a small boost in velocity, if any at all, but it sure helped the black powder burn cleaner. Basically, the barrel fouled with the first shot, then stayed about the same for the rest of the day. I think that wasn't an uncommon practice back in the day though I don't know that it's done much now.

As to mixing smokeless powders - well, seems to me to be a good way to lose a digit or two. I don't think there is any reason to do such a thing now, and I know I sure as heck wouldn't!

[Photog]

The original 454 Casull loads made up by Dick Casull were a triplex load. Can't remember which three powders but I think it was Bullseye, 2400, and Unique.

[Rule3]

Originally Posted by gregintenn

I was reading some old Keith material yesterday, where he went into pretty good detail about the Duplex load he and others developed. The premise seemed solid. Why did this never catch on?

My first post got deleted for some reason.

With the new smokeless powders such as 2400, H110, HS6 they are all that is needed and more for handgun full house loads.

Safer and convenient.

Combining smokeless and black powder today is not a wise idea and there is no data for it.

[keith44spl]

Greg,

I've done a lit'l loading along this bend...A dab of mid to alittle faster burn rated powder under a good sized dollop of
slower burning gave a more complete burn consumption....Kinda like hot priming or magnum primers cartridges.

What with all the new powder avaliable today, don't see much of this kind of loading experimentation going on.

Su Amigo,
Dave

[TSQUARED]

I believe the practise of duplex loads with black powder did not mix powders. Instead it layered a small amount of smokeless powder beneath a case full of black powder. I do not know how the 454 Casull triplex load was configured but I would believe it also layered powders one atop the other.

[Wyo]

Originally Posted by TSQUARED

I believe the practise of duplex loads with black powder did not mix powders. Instead it layered a small amount of smokeless powder beneath a case full of black powder.

That's exactly right, and the effect was much like you might see with a very hot primer. What you got was a much more complete burn of the black powder and much less fouling left in the barrel. The idea wasn't to increase velocity but to make for a cleaner burn.

[Iggy]

I've done the same as WYO and Dave Keith with BP rifle ca'tridges.

Burn a whole lot cleaner and add a leetle bit of steam to the round.

I sure wouldn't do it with anything else.

[JBnTx]

Originally Posted by Photog

The original 454 Casull loads made up by Dick Casull were a triplex load. Can't remember which three powders but I think it was Bullseye, 2400, and Unique.

Bullseye, 2400, and Unique are the Holy Trinity of powders.

I heard that's what powered the Space Shuttle.

[THE PILGRIM]

We used to have a guy from my home town who was famous for carrying sticks of dynamite in his top overall pocket with the fuses burning. That never actually caught on either.
PS: One time I actually assisted him, Oscar McMullen was his name, in blowing out some stumps. Regret to report he just lit that dynamite one at a time.
Duplex load probably not something you should try.

[Alk8944]

Originally Posted by Photog

The original 454 Casull loads made up by Dick Casull were a triplex load. Can't remember which three powders but I think it was Bullseye, 2400, and Unique.

And you were careful to not mention that he blew up several revolvers doing this! Or didn't you know about that part of the story???

The only way duplex loading works is with powders slow enough that it takes a full case and the load is compressed so the different powders remain segregated rather than mixing together. Overall there is no reason to attempt this unless you have access to pressure testing equipment or can absorb the cost of replacing blown-up guns as part of the experimentation process!

[MMA10mm]

Guys, I believe the OP's question about Keith-style duplex loads has nothing to do with mixing powders or even loading two kinds of powders. In fact, it has nothing to do with handgun cartridges. I think we here in the handgun community, who adore and appreciate Keith so much, forget that he was the "original 3-gun shooter" having very advanced skills and ideas in rifle and shotgun shooting and loading as well.

Keith's duplex loads were developed by him and, I believe, Charlie (?) Hopkins - the "H" in the wildcat "OKH" rounds that O'Neil, Keith, & Hopkins "invented." Hopkins was a real gunsmith, and he did the gunsmithing behind the duplex load concept.

Basically, the concept was to build a bottle-necked rifle case with a tube from the primer pocket to about the middle of the case, so the primer flash would ignite the powder charge in the middle, rather than at the back of the case. Keith felt this would give the powder better combustion with less unburnt powder blown out the muzzle.

Hopkins took brass tubing, turned it, threaded it, drilled out the case's primer pocket and threaded the tubing in. He cut the base of the tube for a new pocket, and cut notches in the tube for a custom wrench he could screw the tubing in tight with. Then, he soldered the tube in place.

Obviously, the cases were a real PITA to make, and Keith pointed out they weren't easy to reload either. Lastly, the cases only lasted two or three reloadings anyway, because the tubing eroded so badly from firing.

The named it "duplex," because others were experimenting with mixing powders at the time, but the misnomer would not divulge Keith & Hopkins' secret. This all happened around 1941, and when the war broke out, Keith volunteered his services to the Army and was assigned to Ogden arsenal as a proof tester. He also shared his duplex load idea with the military. They did experiments with 30-06, .50-cal BMG, and even artillery. The Ordnance dept., found the idea worked and worked well, giving several hundred FPS more velocity with only a slight increase in pressure.

The problem was that, even with the engineering and manufacturing capabilities available to the govt during the war, there was no way developed to make the cases on a mass-production scale. The military also got nervous that occassionally the tubes would go down the barrel behind the bullet. In testing this was bad, but in the field it would be unacceptable. (Keith felt this problem was due to poor threading/soldering/fitting of the hand-made tubes, but with no way to draw, stamp, or otherwise make the tubes and cases in one piece, it's a moot point.)

I think that makes it clear why his Duplex system never took off, even though it worked. The other angle is that slower rifle powders became available, which gave similarly higher velocities without significant pressure increases.

[Moonman]

Ole' Elmer LIVED and LOADED on the EDGE.

[papajohn428]

Originally Posted by Photog

The original 454 Casull loads made up by Dick Casull were a triplex load. Can't remember which three powders but I think it was Bullseye, 2400, and Unique.

The bulk of the charge was 2400, in the bottom of the case, then a later of Unique, and a dollop of Bullseye on top. The idea was to keep the pressure curve as straight as possible, and once the 2400 was consumed the Unique would burn, then the Bullseye, with the faster powders bumping the pressure back up as the bullet zoomed down the barrel. Proportions were on the order of 90% 2400, 7% Unique, and 3% Bullseye, or thereabouts. He got some amazing velocities, but he also blew up a lot of guns!

[gregintenn]

Originally Posted by MMA10mm

Guys, I believe the OP's question about Keith-style duplex loads has nothing to do with mixing powders or even loading two kinds of powders. In fact, it has nothing to do with handgun cartridges. I think we here in the handgun community, who adore and appreciate Keith so much, forget that he was the "original 3-gun shooter" having very advanced skills and ideas in rifle and shotgun shooting and loading as well.

Keith's duplex loads were developed by him and, I believe, Charlie (?) Hopkins - the "H" in the wildcat "OKH" rounds that O'Neil, Keith, & Hopkins "invented." Hopkins was a real gunsmith, and he did the gunsmithing behind the duplex load concept.

Basically, the concept was to build a bottle-necked rifle case with a tube from the primer pocket to about the middle of the case, so the primer flash would ignite the powder charge in the middle, rather than at the back of the case. Keith felt this would give the powder better combustion with less unburnt powder blown out the muzzle.

Hopkins took brass tubing, turned it, threaded it, drilled out the case's primer pocket and threaded the tubing in. He cut the base of the tube for a new pocket, and cut notches in the tube for a custom wrench he could screw the tubing in tight with. Then, he soldered the tube in place.

Obviously, the cases were a real PITA to make, and Keith pointed out they weren't easy to reload either. Lastly, the cases only lasted two or three reloadings anyway, because the tubing eroded so badly from firing.

The named it "duplex," because others were experimenting with mixing powders at the time, but the misnomer would not divulge Keith & Hopkins' secret. This all happened around 1941, and when the war broke out, Keith volunteered his services to the Army and was assigned to Ogden arsenal as a proof tester. He also shared his duplex load idea with the military. They did experiments with 30-06, .50-cal BMG, and even artillery. The Ordnance dept., found the idea worked and worked well, giving several hundred FPS more velocity with only a slight increase in pressure.

The problem was that, even with the engineering and manufacturing capabilities available to the govt during the war, there was no way developed to make the cases on a mass-production scale. The military also got nervous that occassionally the tubes would go down the barrel behind the bullet. In testing this was bad, but in the field it would be unacceptable. (Keith felt this problem was due to poor threading/soldering/fitting of the hand-made tubes, but with no way to draw, stamp, or otherwise make the tubes and cases in one piece, it's a moot point.)

I think that makes it clear why his Duplex system never took off, even though it worked. The other angle is that slower rifle powders became available, which gave similarly higher velocities without significant pressure increases.

Thanks to all who responded. This post is correct in it's assumption. I should have been more clear in saying I'm interested in the theory of igniting the powder from the front of the case instead of the rear. You'd think with today's production capabilities, there'd be a way to manufacture brass that could accomplish this.

[WR Moore]

Elmer and his buddy were copying the priming system on fixed artillery rounds-overgrown cartridges you might say. They use a tube primer that runs to just below the base of the projectile with side vents at the shell end to ignite the main charge . On a 105mm, this tube is about the size of your thumb.

The intent of this whole operation is to ignite the powder charge from the front end, using the developed pressure to hold the charge in place while it burns, rather than it possibly being pushed down the bore after the projectile. Obviously, artillery rounds use a whole lot more powder than small arms.

The simplist answer about why this never transferred to small arms is easy-the gain isn't worth the expense. Also, we have a vastly larger selection of powders than they had in the 1930s.

[Bomberman]

This is the inside of a 105MM shell...as you can see this type of priming is used on the larger cannon shells and down to as small as 20MM. Loading this type of priming system into anything smaller is just too cost prohibitive. Even though it may be more efficient, it's just not that much more efficient than the standard priming we are all familiar with in the smaller cartridges.