Duplex load

[nueces5]

hello everyone
I'd like to try duplex load, never do this. I will use win 231 and a gunpowder similar to the grain of the R19, a little bigger and much slower.
The question is: how do I make the small grains of win231 stay at the base, near the primer?

[BLAHUT]

You can try putting 1 layer of cut wad of news print over the 231, or 1 layer of a cut wad of cigarette paper over the 231 ? other powder will hold in place and burn through ?

[1006]

I am guessing that you find a powder you can compress in the cartridges that you are loading, that should hold it in position.

[rbuck351]

The only reason I use duplex loads is to be able to use a powder that is too slow for anything I shoot. I acquired a large quantity of 5010 and have nothing I can use it in. I fill a case with 5010 enough to get a slightly compressed load and fire it.normally I get a low velocity and unburned powder in the barrel. Then I lighten the 5010 by three grains and put three grains of a powder like 231 over the primer and the lighter load of 5010 on top. This keeps the different powders in place as I continue to increase the fast powder and decrease the 5010.

I have only duplex loaded cast boolits and when the powder burn cleans up I usually have a good cast bullet load.

[M-Tecs]

https://castboolits.gunloads.com/showthread.php?244470-Duplex-loads

[Harter66]

Light compression is the answer in any duplex or triplex loads . Seek out PO Ackley Hand Book for shooters and reloaders it has applied data for the 45 Magnum and 454 (45) Casaull .

[nueces5]

what occurs to me is that the grain size of 231 is much smaller than slow gunpowder, and so I don't know if 231 is going to come out of place

[stubshaft]

what occurs to me is that the grain size of 231 is much smaller than slow gunpowder, and so I don't know if 231 is going to come out of place

If it is compressed it will not migrate as there would be minimal space for it.

[JonB_in_Glencoe]

what occurs to me is that the grain size of 231 is much smaller than slow gunpowder, and so I don't know if 231 is going to come out of place

As mentioned, if it's compressed, you should be good.
But, if you prefer to confirm this, try making a load in a clear tube, similar to the size of the base of your case, and see how the powder granules behave when agitated.

[Larry Gibson]

What cartridge?

[TD1886]

I've been shooting duplex loads with slow surplus powder for decades. I've shot it in everything, so the cartridge doesn't really matter except it's more difficult with the small ones with their smaller capacity. I've even shot duplex load in shot shells. My currect 45-70 duplex load is one I've, again, be using for decades. Want to know how good it is? I can shoot gallon water jugs at 400 yards with the open sights. To say I have my 45-70 load perfected would be an understatement. I have a duplex load for the 308 that duplicates 4350 in any loading. This load also transfers over to similar capacity cartridges. Enough on that.

I make my loads so they fill up the case. I don't use any kind of paper over the small charge of fast powder to keep it in place and I don't recommend it. I use two powder measures for using duplex loads-one for the slow powder and one for the booster. PAY ATTENTION TO WHAT YOU ARE DOING WITH THIS. YOU CAN GUESS WHY.

Yup I've enjoyed the cheap surplus powder duplexing them with a big smile on my face.

[Nobade]

Likewise here. I have accumulated quite a bit of surplus $2/lb powder and pretty much that's all I use in most rifle cartridges. The only thing I would add is maybe don't use something as fast as 231 for the kicker. I find the pressure spikes too fast with powders like that, and much prefer something in the range of blue dot, 4227, 2400, etc. You get a smoother pressure trace and usually better accuracy.

[TD1886]

Likewise here. I have accumulated quite a bit of surplus $2/lb powder and pretty much that's all I use in most rifle cartridges. The only thing I would add is maybe don't use something as fast as 231 for the kicker. I find the pressure spikes too fast with powders like that, and much prefer something in the range of blue dot, 4227, 2400, etc. You get a smoother pressure trace and usually better accuracy.

You're right about the pressure spikes with the faster booster (which you much use in the very small cases as they don't take up much room) but I use H4198 for the larger capacity cases. Be careful of the fast powders in small capacity case, for example I was trying to develop a duplex load for the 7.62x39 and the booster was HP 38. It went from normal to really expanding the web on the next tenth grain up on loading. I determined that's not a good booster for what I was wanting. The H4198 did work, but there wasn't enough space left with the surplus powder to get any decent velocity. Those are the kind of things you will find and run into. BE CAREFUL in fact extra careful.

[nueces5]

What cartridge?

308 win

[nueces5]

Good morning, I have read everything and I think I can use win296, Alliant 2400 or something faster as a booster, which is manufactured in Argentina called UW2000, which is a double-based gunpowder, slower than win231 and is generally used in shotguns .
I'm going to do 5 charges today, using 3 grains of booster, and topping off with slow gunpowder. The slow gunpowder that I am going to use is made to load the 50BMG, so I don't think there is an overload problem. I'll use a heavy boolit for the 308, as it is 314299 drawn to 309.
Since I have some berdan brass, the first one is going to be RWS.
Is it okay to start with 3 grains of H2400?

[MUSTANG]

Some posts I made on duplexing back in previous "Powder Shortage" times. The first is for .308/7.62 in a M1a. The others are for .223/5.56 loading.



https://castboolits.gunloads.com/showthread.php?169370-WC860-in-M1a&highlight=

https://castboolits.gunloads.com/showthread.php?241228-WC872-in-223%92s&highlight=

https://castboolits.gunloads.com/showthread.php?160094-WC860-in-223-5-56-Yes-But&highlight=

[TD1886]

I'm going to tell y'all how to do this, but of course many won't listen. Let's take the 308. Let's take 867 surplus. For the booster H4198 since it has shorter kernels then IMR 4198. The charge of 867 will be 38 grains, the bullet weight 172 grains. You should have a chronograph. You start with a little booster say 4 to 5 grains. You shoot 3-5 test shots across the chrono. If you're using a bolt action rifle this part is easier. You want to extract the case gently. Tap the case mouth on a piece of white paper. See if you get any unburned powder. Next pull the bolt and look through the bore for unburned powder, last look at ES and SD on the chrono. If you find any unburned powder and the ES and SD are rather high you need more booster. When the case and bore are free from unburned powder and the ES and SD are low you hit the spot. I'm going to tell you the weight of the booster in my rifle and it's 6.5 grains. Again the main load it 38 grains. Don't shoot it with a much heavier bullet. Don't be fooled you can't go wrong because the main charge is a very very slow powder because the booster turns it into kind of a different burn rate........a faster one!! BTW I get single digit ES's and SD's.

[Maven]

Good tutorial, TD1886!

[TD1886]

Good tutorial, TD1886!

Thanks Maven. I want those trying duplex to be safe with it.

[nueces5]

Thanks TD1886, tomorrow I will start!

[TD1886]

Thanks TD1886, tomorrow I will start!

You're welcome, thumbs up and good luck.

[nueces5]

Well, the first test is with two shots of 3, 3.5 and 4 grains of H2400, the rest of the brass with a very slow gunpowder, which is used for the .50 BMG here in Argentina.
I couldn't use the chronograph to measure speed, but it shows that it is a powerful shot.
All loads within an inch at 50m, with mediocre support. So more than satisfied.
Now I must measure with the chrono and see which is the most convenient load,

[uscra112]

Sure would like to see some pressure/time curves for "successful" loads.

I admit the utility of it given the difficulty in obtaining better powders. But am might glad I'm not short of any that I commonly use nowadays.

[deces]

I have a question, are there any reloading books that cover Duplex loads at depth? I'd really like to read more about this in print.

[nueces5]

I have a question, are there any reloading books that cover Duplex loads at depth? I'd really like to read more about this in print.

I think that every time the manuals show less and less, to avoid having legal problems
There is much more info here on the forum.

[Nobade]

I really doubt that is something you are going to find anything in books since it is so far away from the norm. Your best resource is right here from people who have done it and written about the results. Remember, we aren't trying for super performance. We're just trying to use up super cheap and otherwise unsuitable gunpowder in an application it is not designed to be used in.

[MUSTANG]

Nueces5:

Any further testing and performance reports?

[Maven]

All, I've tried duplexing WC 860 (with WLR magnum primers) with several propellants in my "as issued" Type 56 SKS (spike bayonet). ~3gr. CLAYs + 21gr. 860 was a waste of time as was 4gr. Lil' Gun + 20gr. 860: The first wouldn't eject and left the cases quite sooty whereas the second tossed them pretty vigorously, but left unburned powder in the magazine well. Neither was especially accurate @ 50 yd. from a rest. However, last week I tested Ian's (from The Art & Science site) suggestion to use 4.5gr. Lil' Gun + 19.5gr. WC 860 and was rewarded with great accuracy, mild ejection, and clean cases. Btw, the CB was a ~160gr. C.E. Harris design + gas check, sized to .3155" and seated @ 2.125". No crimp was applied. That particular powder combination and bullet seating depth allowed for enough compression to keep the starter charge in place.