what is the reason for a duplex load how is it done

[catkiller45]

I was told you can use a duplex load with black powder cartridge..What is the reason for this? How do you use it and is it a safe way to shoot cast bullets? My question is for hunting loads,as I know you cant duplex for most competition shooting...
How does one know what and how much to use for duplex loads....Is it true you can get more shots without wiping the barrel out? Thanks:coffee:

[405]

Well,
Duplex loads are used to help reduce the build-up of BP fouling thus reducing the need to wipe or clean between shots to mantain top accuracy over a string of shots. The amount of BP fouling and how it affects accuracy through multiple-shot strings varies quite a bit (load to load, shooter to shooter) so the need for a "cleaner" burning round may depend???? If your basic BPCR load shoots well and you don't experience chambering problems after a few shots it may not at all be needed for a "hunting" load. Maybe--- hunt close, shoot straight, shoot once?

I think both Lyman and Mattews have some info using duplex loads. The rules of thumb (that may have all kinds of exceptions) is that the pressure equivalent ratio between smokeless and black is about 3:1. AND The smokeless should not exceed about 10% of the black. So a duplex load that calls for 50 grains of black plus 5 grains of smokeless would yield a pressure equivalent of about 65 grains of black. The common smokeless powders used for duplex loads include Unique, 4759 and 5744 and others. Since smokeless powders carry so much more potential energy per unit of weight and volume approach these types of loads with the greatest care!

Duplex loads are loaded using the same technique that is used for loading BPCR loads. First drop the smokeless- then the black- then the wad- then the bullet lightly compresses the powder column at final seating depth.

[KCSO]

Someone back in the early days of smokless decided this was easier than proper load development and it carried through. Straight black will shoot just as good as anything and for those too busy to swab every 10 shots there is always that newfangled untested smokless stuff.

[45 2.1]

Schuetzen shooters were duplexing and triplexing BP loads long before smokeless came up, then they used it to get better scores for those high dollar match shoots. If you research what was going on, you will find that the top shooters regarded the smokeless duplex BP loads and later smokeless loads as less tiring and more accurate than the straight BP loads, even with the cross strip patched muzzle loaded BP rifles. Breach seating brought a new wave of accuracy in itself. Their words, not mine.

[freedom475]

For hunting you will gain very little from duplexing because you probly won't shoot very many shots in a row.

Remember that your POI will be different with a clean barrel so when working a hunting load it is wise to shoot one shot then clean the barrel, then shoot another. This way you will replicate the clean barrel POI you will have when hunting.(unless you fire off a fouling shot when getting out of the truck:mrgreen:)

[EDK]

POA/POI from a clean barrel

Get out your copy of Mike Venturino's SHOOTING BUFFALO RIFLES OF THE OLD WEST and start reading the bottom paragraph of page 244 on. When two guys like Mike and his amigo, Steve Garbe, tell the story on themselves, there's hope for us less experienced shooters.

If you don't have the book, send Mike some yankee dollars for the hard bound copy and have him autograph it. Reading it will save you a lot of time and money by not having to "re-invent the wheel" and guide you in the right direction.

:Fire::cbpour::redneck:

[Gellot Wilde]

I think that in the 'Primer' they say that duplex loads are actually more inconsistant pressure-wise than straight black.

I have used them, but to be honest I can get great results from straight black, I think after all's been said and done the straight black works best.

[KCSO]

From a famoous BPCR shooter, "He!! If I told folks I was putting a pinch of HorseS#!t in the bottom of my cases by next year EVERYONE would be shooting horses#!T". Things haven't changed that much in the last hundred years. Mostly I've heard folks talking about how so and so shoots duplex and how good he shoots, but in actual practice I have not found it an advantage.

[runnin lead]

Wouldnt bat $#it preform superior to horse s#!t do to its high nitrate content

Jim

[Gellot Wilde]

needs to be run through a screen first, $#it don't. :drinks:

[Idaho Sharpshooter]

actually, breech seating predates smokeless powder by a couple decades. Early Schuetzen competitors found that the "breech-muzzle loading rifles were in use in the late 1860's. The logic is that by pushing a bullet down from the muzzle eliminates the possibility of a burr or two being formed on the base and affecting impact from shot to shot. You also eliminate having to use a blow tube or patching the rifle between shots. Read Pope's book if you want to know what was happening from 1870 to 1920 and now is being revived.

Rich

Having competed at Golden and Raton twenty years ago, I have some idea of what I am talking about.

PS: you haven't heard anybody talk about duplexing for BPCRS, it has been illegal since Day One. This year it was outlawed for the long range matches as well. Straight black only.

[northmn]

I played with duplexing. First you do not have to use the 10% or what ever max. I used to use about 5 grs. 4759 in my 45-70 with 60-65 grs. black (depending on the bullet) Matthews states that 1-3, meaning that 1 gr of 4759 give you 3 grains of black. Over the chronograph there is a velocity gain. Its kind of like letting yourself experience a 45-90 in your 45-70. It burns cleaner. Its also a pain for loading as I like to weigh charges for consistant compression. You also may find a little better accuracy with lighter charges of smokeless. Some used to duplex 4f under 2f for better ignition. If I were shooting Swiss I likely would not duplex, if it were as good as they say.

Northmn