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Old January 26, 2012, 09:10 AM   #1
savagelover
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using duplex loads question.

So can someone please explain the reason for using the duplex loads in the first place..I have read some about them but never really understood the reason behind them..Is this so one does not have to clean the barrel and or the brass after shooting..

Does the duplex load keep your brass that much cleaner than straight black powder?

Will the barrel still need cleaning with a black powder solvent as well?

And how about powder compression?
Thanks for reading my post and if you have any advice,please feel free to share it with me.. John
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Old January 26, 2012, 10:09 AM   #2
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By 'duplex loads' do you mean real black powder mixed with substitute black powder? Or real/substitute black powder mixed with smokeless powder? Or something else?
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Old January 26, 2012, 10:33 AM   #3
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Think of duplex loads as ignition augentation, and another internal ballistics component of finding that load the rifle/bullet combination likes.

After many years I settled on 9gr of 4759 under 95gr of 1F under a 580gr pure lead/paper-patched Ballard for my Sharps. The bullet/card-wad/grease wad/powder column is only very, very lightly compressed and the result is 1" groups -- but I still have to clean the barrel/wash the cases afterwards.

No free lunch....
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Old January 26, 2012, 11:40 PM   #4
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Hello, savagelover. The practice of du-plexing blackpowder with smokeless is as old as smokeless powders themselves. The old-time match shooters ..both bench & the offhand schuetzen shooters at the beginning of the 20th century used them.
The idea is to have a clean burning load which permits multiple shots without the need to clean after each shot.
I had heard of the practice for years..never thought much about it..that is until I started working with an original Ballard No. 3 match rifle in .25-25 Stevens.
Since this is a cast action, and it left the factory in the 1880's..I have decided to stick with black powder.
I have been using Swiss 3FG. With a 1gr. charge of SR PB next to primer, & 22.5gr. black, a 1/16" SPG grease "cookie" sandwiched between two 1/32" beeswax wads..the bore is left looking like a smokeless load had been fired..even the grooves were clean.
Best of all..4 out of 5 grouped into 3/8" at 50yds.
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Old January 27, 2012, 01:37 AM   #5
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That is a loaded question (har har )

I've always thought that some people used real BP in conjunction with synthetics usually when they were nearly out of BP but they were able to pick up some Blackhorn 209 locally. It won't ignite using regular caps or flint, so they would load half a measure of BP and use Blackhorn for the rest of the charge, so the BP would ignite the Blackhorn.

I've heard of the term "duplex load" for several different situations. The first was when I read about military projects where they loaded two projectiles in a rifle cartridge where they had two bullets stacked on top of each other, each weighed half as much as a standard projectile, so they would spread a little. The current .410 self defense rounds do that with the little slugs.

They have duplex shotgun shells for game loads where they mix large shot with small shot, so you get the punch of the big shot interspersed with the bleed out of the small shot. The buck and ball worked like that and some of the .410 self defense loads mix large birdshot with buck.

While they were developing .454 Casull and .454 Linebaugh, they would use two or three different powders to get different burn rates and more power, they called those duplex loads.
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Old January 27, 2012, 08:37 AM   #6
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Interesting very interesting...Thanks so much for the explaintion..
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Old January 27, 2012, 09:54 AM   #7
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Yep, duplexing with a smokeless powder significantly reduces fouling in the gun.

Most of the people I know who do it use a flake pistol powder like Red Dot or Unique.
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Old January 27, 2012, 02:05 PM   #8
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Mike---I was thinking of using Unique..I am thinking about 7-8 grains...
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Old January 27, 2012, 03:22 PM   #9
Mike Irwin
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'Mike---I was thinking of using Unique..I am thinking about 7-8 grains... '

Uhm....

What cartridge are you shooting?

What load? Powder granulation, load in grains, bullet weight?

Everything I've always read indicates to start low and slowly work up, watching for any indications that something is amiss while keeping an eye on powder fouling levels.

You start low and work your way up because, unlike black powder, smokeless powders are progressive burning and, in a rifle designed for black powder, pressure levels can quickly rise to danger levels if EXTREME CAUTION is not exercised!

I'm not sure that 8 grains of Unique is proper for any cartridge save one of the really huge ones like the .45-120 or .50-140.

I know I would NEVER start out with that amount, and I'd never use that much in a cartridge like the .45-70 where that amount could be well over 10% of total powder weight.


I'm going to suggest checking out one of the dedicated black powder forums like www.BPCR.net

The user forums are here: http://www.bpcr.net/index-a.htm
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Old January 27, 2012, 05:34 PM   #10
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Your not understanding it..This is unique and black pwder...the unique and then the black n top ....the unique will make the black burn cleaner..
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Old January 27, 2012, 05:38 PM   #11
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I use 11 grains of Unique for a good bang in my .357 handloads. That 7-8 grains would be quite a starter boost for a charge of bp. I'd double check the research on that.
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Old January 27, 2012, 06:14 PM   #12
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so what is 10 percent of 70? 70 being grains of black powder.
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Old January 27, 2012, 08:29 PM   #13
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"Your not understanding it..This is unique and black pwder...the unique and then the black n top ....the unique will make the black burn cleaner.."

I fully understand the concept of a duplex load of smokeless and black powder. I've seen it done many times, and I know that it takes an iterative approach and a LOT of caution!

I also fully understand that putting smokeless powder under black powder does NOT in any way, shape, or form negate the fact that smokeless powder is VERY different in its burning characteristics.

As I stated, the amount of smokeless powder used MUST be balanced against the volume of the case, the bullet weight, the amount of black powder used in the cartridge, and the age and strength of the firearm being used.

Screwing any of those and you run the risk of damaging your gun or injuring yourself.

You CANNOT wing this.

You CANNOT simply use a 10% estimation and go from there.

I've given you a resource that is LOADED with people who do this on a regular basis, people who understand how to do it, and people who understand the nuances involved in doing it safely.

USE THE RESOURCE I'VE GIVE YOU AND DON'T WING IT.

But, if you do decide to do it seat of your pants, and you break your rifle or injure yourself, be sure to post some pictures.
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Old January 28, 2012, 05:27 AM   #14
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Quote:
But, if you do decide to do it seat of your pants, and you break your rifle or injure yourself, be sure to post some pictures.
It's best not to mention muzzle loader and smokeless in the same sentence let alone introduce bp and smokeless in a rifle barrel but if you must do so have your family take pics for the next guy wanting to try it.
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Old January 28, 2012, 09:04 AM   #15
savagelover
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Mike----My faught....I am the one not understanding what yu were say...Please forgive my ignorance....You are 100 percent correct..One has to know full well what he is dealing with when doing this..I followed Matthews readings on this a few years ago but never tried it myself...So I am taking your advice and will check the above site....Thanks for putting me in the right direction....John
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Old January 28, 2012, 11:24 AM   #16
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After gooing bacl over Spencer Wolfs article about it I have a lot better understanding f the duplex loads..His book is very well written and very informative..I see he only mentioned 2 different SL powders to use and it so happens I have them here as well...Thanks for all the advice..John
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Old January 28, 2012, 11:35 AM   #17
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duplex

Don't use duplex any more. NRA rules changed. When I did here is what I used. 40-65----5gr 4227, under 53 gr 2f goex, 410gr rcbs bullet.
4570----5gr 4759, under 57gr 2f goex, 535 lyman postel. Win primer with both. Never new any one using unique. The guy is right DON'T WING IT!!!!!!!!! Both rifles were modern sharps made in Montana. Also the recoil was quite noticable over a reg black load.
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Old January 28, 2012, 11:59 AM   #18
Mike Irwin
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NRA Black Powder Cartridge Rifle Silhouette Competition rules have never allowed the use of duplex loads.

As associate editor of American Rifleman in 1992 I attended the BPCRSCs at the Whittington Center in Raton, New Mexico.

One of the things that competition staff did, on a random basis while shooters were on the line (before the string started, of course), was pull several cartridges from their ammo loads and break them down to examine them for any traces of a duplex load.

As far as I know no one was ever caught cheating that way.

That said, there are more reasons to shoot black powder cartridges than NRA competition. I know more than a few people who do it just because they want to, they have historic rifles, and they can.


As for what powders are used, I know Unique is occasionally mentioned because it is so flexible and it's also historic in that it was one of our earlier smokeless powders.

Others used are the IMR Sporting Rifle powders 4759 (? can't remember the numbers off hand).

In the "long ago and far away times" when smokeless powder was new, there were smokeless powders called "bulk replacement powders."

These were smokeless powders that were loaded by volume just as black powder was.

Those powders have been off the market for years, unfortunately.

The closest thing we now have to a bulk smokeless replacement is the relatively new Trail Boss. In larger cases like my .44 Special it's been exceptional.

While it is close to a bulk replacement powder, it is NOT a true bulk replacement powder and cannot be treated as such.

BUT, I do not know of anyone who is using Trail Boss as a duplex powder in black powder loads, but I suspect that they are out there. Trail Boss has answered a lot of prayers for people who have wanted a very bulky but low pressure powder for a long time.

Another good resource would likely be www.castboolits.gunloads.com
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Old January 28, 2012, 12:00 PM   #19
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OK, John, I'm glad that we're on the same page.

You had me really worried there.

You still haven't answered the question, though, and I'm dying to know, what cartridge and what gun are you shooting?
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Old January 28, 2012, 03:31 PM   #20
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Duplex

Some clubs would allow duplex, I don't know any now. Lodi would allow duplex yrs ago in their match. Maby they still do????
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Old January 28, 2012, 04:04 PM   #21
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You still haven't answered the question, though, and I'm dying to know, what cartridge and what gun are you shooting?
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I am using a Pedersoli Sharps rifle..In 45-70 of course with 535 grain postell cast 20-1

All I am after or loking for is a load to make it burn cleaner....I no longer compete except against myself...Thanks for all your information...
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Old January 29, 2012, 08:53 AM   #22
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Think of duplex loads as ignition augentation
If anything, I feel it's the smokeless that needs a kick from black powder to get burning, not vice versa. In large artillary, such as the 16" naval guns, a 2 kilogram bag of black powder goes between the 600 pounds of smokeless powder and the primer to kick off the smokeless charge if I remember correctly. The black powder charge acts as a booster for the primer.
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Old January 29, 2012, 10:53 AM   #23
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Little bit different scenario when discussing big guns and their powders, and one that's really not applicable to small arms.

In large guns the black powder booster is used because its simply not possible to ignite that much smokeless powder evenly with a simple primer.

At one time experiments were tried using smokeless powder boosters, but they had undesirable effects that required a lot of ancillary testing to get the booster and the main charge synched up, plus the ignition temperature on smokeless tends to be a lot higher.

Using black powder made the whole process a lot simpler from a controlled ignition stand point.
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Old January 29, 2012, 11:22 AM   #24
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Using UNIQUE to make something burn cleaner! UNIQUE!
How do you know BP is filthy? UNIQUE makes it cleaner!

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Old January 29, 2012, 11:56 AM   #25
savagelover
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Using UNIQUE to make something burn cleaner! UNIQUE!
How do you know BP is filthy? UNIQUE makes it cleaner!

What are you saying here..Is it a riddle or what....more likely WHAT..LOL
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