Duplex loads...faster powder on top?

[JonB]

A recent post (by Ricochet) about Duplexing a slow mil surp powder, with a twist had me thinking, why hasn't this been done before?

The twist is putting the faster powder on top of the slower powder. It sure would be a more gentle rise in pressure for a more gentle launch, which would seemingly be an advantage for cast bullets.

http://castboolits.gunloads.com/sho...slow-powders&p=4088313&viewfull=1#post4088313

 

[Brad]

Interesting concept. Would be interesting to see chrony data with just slow burner vs slow burner with fast burner on top and fast burner on bottom.

 

[Ian]

Quite a few people have it that way, they just don't write about it.

I dabbled in this a little after working up the duplex load the normal way and basically just reversing the order. Ricochet is correct, putting the booster on top does work and does change the launch characteristics, sometimes in a very favorable direction, but sometimes not. I never really understood why it slows the burn curve to do it like that, but I can follow his logic and it makes sense. The one thing I had trouble with was getting the slow stuff to go off consistently, which is why I used boosters in the first place and relied on the slow powder payload in front to make the burn curve long and low. One load I did try that worked really well was booster at both ends. The booster was about 1/8 of the total powder charge, and I put 1/3 on top of the primer and 2/3 under the bullet. It worked great but is way more trouble than its worth for me to mess with. Maybe LG will test a duplex load both ways and show the pressure map for general edification, it would sure be interesting.

 

[Eutectic]

I dabbled in this a little after working up the duplex load the normal way and basically just reversing the order.

I think it's about time someone brought back ol' Elmer Keith's front ignition along with his duplex loads! The .333 OKH in the 40's was another of Keith's 'brain' children that went on to becoming the .338 family.

I shot with a guy named Ralph all the time here... What a good guy! What a shot! WHAT A HANDGUN SHOT!!! The cool thing was Ralph was one of Elmer's best friends.!! Elmer had passed... I know a lot about Elmer Keith because of Ralph. Sadly Ralph has gone to his maker as well.... Man I miss him! There was a handgun shot! (I repeat myself) Trained by the 'man' himself! We were talking one day and the .333 OKH came up... "Yeah... O'Neil, Keith, and Hopkins.... They even had a front ignition tube." I was preaching to the choir...
Ralph got up without a word and left.... He came back and handed me an old box of Super Speed .30-06 brass. "What's this?" I asked. "Elmer gave me those.... O'Neil I think it was had already machined and installed the front ignition tube in these new cases and they were never formed!" I looked them over like a hawk. "These are something else Ralph! Bet there's not many of them still around!"

I handed the box back..... "No... you keep'em Pete... Elmer would love for somebody to talk about them that actually knew how they were made."

So here's a picture of the old, but nice shape box. I photoed a primer pocket showing the tube.... It was screwed in! I also picked a case with an off center flash hole which we dealt with that you younger guys don't know about. It still has a brass chip from machining! Look into the case mouth. At the 3:00 O'clock edge you will see the tube and opening. Sorry it is really hard to get light inside for a sharp picture.
And I'm sure not going to cut one open from a full pristine box!!

Pete

 

[Ian]

I think Col. Harrison worked with those too, if memory serves, and Mann may have experimented with an ignition tube as well. I read too much and after a while it all starts to run together.

 

[Brad]

Does anyone have any toys neater than Pete? Maybe a few rifles from Smokeywolf but otherwise he takes the cake.

 

[Eutectic]

Here's another mouth view. I tried to show some depth at an angle and just made it look off center! New camera needed!!!

Pete

 

[Brad]

I can remember Elmer referring to these as "duplex" loads. I believe he experimented with it in 50 cal and 20 MM rounds for the military. Got more velocity and less throat erosion.

Elmer was truly a great experimenter. Elmer is known mostly for handgun bullets and load but did so much with rifles too. He was the right man in the right era. Today the lawyers would shut him up and half of this would never be done. We all owe him a huge debt of gratitude.

 

[Brad]

http://www.elmerkeithshoot.org/GA/1982_10_Compressed_Rifle_Charges.pdf

Here is a little writing by Elmer regarding his duplex cases.

 

[Eutectic]

Elmer was truly a great experimenter. Elmer is known mostly for handgun bullets and load but did so much with rifles too. He was the right man in the right era. Today the lawyers would shut him up and half of this would never be done. We all owe him a huge debt of gratitude.

He was a grand old man Brad..

For a while we had the "Elmer Keith Museum" here in Salmon. I worked there quite a bit hanging up Elmer's game heads and what stuff Ted Keith would let us have. No guns..... I worked on the busier days as Doug and Shannon knew I knew Elmer. It was amazing what some vacationers talked about.... How Elmer had answered their letters from the "Dope Bag" in the American Rifleman. In the lulls I would set at Elmer's desk in the area we had roped off to the public. Elmer had a comfortable chair..... I got studying the contents of his top drawer. It would look like a cluttered mess of junk to most... but interesting to me... I saw a pattern... Most everything in the drawer was a failure of some kind! Somewhere in his writings it had been talked about... One slow morning I saw some expanded bullets towards the back... They were actually gnarled jackets without lead. They had old dried blood and meat on them. I knew from the multiple cannelures that Remington made them.. But 'them' what? I stared at two base sections of jackets. They were smaller than a .45-70 but bigger than .38-55.... Then I remembered Elmer's story on the .400 Whelen he used as a big game gun in the 20's. How it failed horribly when he drove some .40-82 260 gr Remington factory bullets way to fast and hunted with them...

Ralph had told me Elmer 'kept' things... both good and bad or controversial. If a Jack O'connor fan doubted Elmer's story to Elmer's face..... Ralph said ol' Elmer might just 'pull out' proof and show him... "You think so, huh? Well look at this... Like I said isn't it?"

Those failures stared at me from the desk drawer!!!

Pete

 

[Brad]

Hold on a second. You sat at Elmer's desk and went thru the drawers?
I am in total awe. I don't suppose you took photos, did you?

This may well be the thread that left me the most speechless.

 

[fiver]

if I remember this right he started the tube thing with a 45-70.

 

[Harry O-1]

The original .454 Casull had a TRIPLEX load. The original load was in .45 Colt cases. There were three different powders used and they were compressed with the bullet so they would not mix with handling. I once had the specific load, but doubt that I could find it today.

The load closest to the primer was an easy to ignite medium speed powder (like Unique). The primer ignited that one. The next powder was the majority of the load. It was a hard to ignite rifle powder (which one, I don't remember). The Unique was supposed to ignite that. The top powder was a small amount of a very fast pistol powder (like Bullseye). This was supposed to give the bullet a final kick in the butt when it was well into the barrel and the pressure was dropping. Remember that a number of early .454 guns were accidently destroyed when these loads were being tested.

With longer cases and improved powders, the triplex load was dropped.

 

[Eutectic]

Hold on a second. You sat at Elmer's desk and went thru the drawers?
I am in total awe. I don't suppose you took photos, did you?

Sadly, my museum stuff were lost with a hard drive..... More stuff I really miss too!

BUT! I WAS WORKING ON TWO PROJECTS WITH PERMISSION. (from the top drawer of his desk) I had those two pictures on a CD!

The item of most significance in his desk Elmer hated! Yet he kept a reminder in that desk for many, many, years... Elmer was young when this hate started. I finished the story about it to a 3ft x 4ft poster-like display (from one of his books) with the reason he kept that when most people wouldn't.
Ralph had talked to Elmer about what happened and Elmer was still mad 60 years later! (this was in 1979.) Ralph gave me some details that proved in my mind what the item was kept for and where it came from.. Alright! This item is a loaded cartridge! Ralph knew I liked this cartridge. He knew my first center-fire repeater was so chambered. I mentioned to Ralph that I wished Elmer was alive and with us at that moment so I could convince Elmer he was wrong about it..... Ralph gave me that twisted little grin he had and giggled out.... "Boy Pete! I'd sure of liked to see that!"
This picture I'm holding back for a bit looking for something about the poster. I never saw this poster again when Ted Keith moved the museum to Cabela's in Boise. We weren't making the money he thought he deserved!

Because the museum moved my second poster was never done. This was just a unique item to Elmer and he was nether hot or cold about it. He wrote about it in "Gun Notes". This picture is attached... I'll send the other a bit later.

I was in Elmer's reloading room once as well......
Pete

 

[KHornet]

I always felt that I was better off letting others screw around with duplex loadings.
Have never regreted that decision. Or maybe I am just to darn set I'm my ways.

Paul

 

[Brad]

Pete, what caliber is that bullet? Looks like a really long and heavy 6.5. Gonna need a fast twist for that to stabilize.

 

[Eutectic]

Here's the article Elmer wrote on the bullet above from Guns & Ammo February 1963 or in Gun Notes volume 1. One of the very few times Elmer spoke of the .264 in 'positive' comments!!!! A 200 grain Barnes .264 out of Elmer's desk...

Pete

 

[smokeywolf]

Does anyone have any toys neater than Pete? Maybe a few rifles from Smokeywolf but otherwise he takes the cake.

Just because I haven't been commenting doesn't mean I haven't been listening.

I've never duplexed smokeless with smokeless. I learned a long time ago, when your knowledge is greatly inferior to others, it's usually better to just shut up and listen.
I'm listening.

 

[Brad]

Smokey, you have some damn fine rifles with a story behind them.

Sadly, I just own some stuff a factory put out. Some are nice but none have a story.

I too know nothing of duplexing. I haven't done it except a few BP loads. It is confusing that Elmer called something "duplexing" when it had nothing to do with using 2 powders.

 

[Eutectic]

It is confusing that Elmer called something "duplexing" when it had nothing to do with using 2 powders.

Bob Hagel referred to the process Elmer used as a 'patented' process and not two different powders being used. The only thing I can think of is opposing forces..... Elmer mentions the powder burning back into the case as the bullet accelerates opposite. A polar force? I know duplex is sometimes used as a definition for certain opposing forces? Maybe a Physicist will 'chime' in and give us the answer??

Pete