Duplex Powder

Retrieved: 08/27/2016

Alliant Unique
Accurate No. 9
Accurate 5744
IMR 3031
Hodgdon H335
IMR 4064
IMR 4350

My question is which powder do you all think would be the best for the duplex? Wanting to go 55 grs. of the Cartridge Grade and 5 grs. of the other. Any ideas would be much appreciated.

hellgate:
Some of the older loading manuals (Lyman, maybe) have info on using duplex loads. Also you might want to check with the Cast Bullet Association for proven loads. It is easy to get into trouble with the duplex loads so I would recommend published loads from reliable sources. If my memory serves, I believe the shotgun powders were more typically used as the smokeless booster. I've never loaded them as I also believe they are not allowed in SASS shoots and quite a few of the BP target matches. They do, however reduce fouling.

PJ Hardtack:
Of all the powders you list, 5744 would be the one I'd use - 4.2 grs of it wirh 55 BP. Other powders to consider are SR4759 and 4198, long used for duplexing BPCRs.

Lumpy Grits:
No need to duplex with the correct load ;)

More issues than it's worth.

quigleysharps4570:
Thanks for the input guys. Believe I'll give 5744 a whirl.

Hellgate I don't do the matches so that won't be an issue... my shooting is all done behind the house or at a friends place on the river, so anything goes.

You're right Lumpy...but I'm just wanting to play. :)

Junkman:
What do you intend to accomplish by loading the cartridges with a duplex load?

Delmonico:
More important, has anyone read this?

http://www.cascity.com/forumhall/index.php/topic,40688.0.html

Lumpy Grits:
I shoot/load for BPCR, everyone that I know who started out thinking duplex was the way to go has stopped doing so. Due to issues ranging from cases swelling at the head due to the pressure spike of the smokeless powder, to bulged chambers at the chamber mouth for the same reason.

I will NOT duplex... It buys you not one thing.

PJ Hardtack:
Anyone who prefers not to shoot duplex loads in BPCRs is welcome to do so. Until such time as I feel I am endangering myself, my guns or anyone else, I shall continue to do so.

There is a history of shooting duplex loading... The following from "The Breech-Loading Single Shot Rifle" by Ned Roberts and Ken waters, noted riflemen and ballistic experimenters.

"Some riflemen discovered that loading about 8 grs of Dupont No.1 Rifle smokeless powder in the bottom of the shell as a priming charge, and filling the rest of the shell with black powder with a cardboard or blotting paper wad over it, resulted in as fine accuracy with a breech seated or muzzle loaded bullet, WITHOUT WIPING THE BORE AFTER EACH SHOT, as was obtained with black powder and wiping the bore.

This smokeless powder priming caused the rifle to shoot very clean indeed by preventing the black powder residue from fouling the bore, so that A HUNDRED SHOTS OR MORE COULD BE FIRED WITHOUT WIPING THE BORE and as fine accuracy secured with the last shot as with the first.

In a very short time, therefore, practically ALL Schuetzen riflemen had adopted it as a priming charge, and many used this duplex loading until the manufacture of Dupont No.1 powder was discontinued in 1926.

This powder did not pit or corrode the barrel when used alone because the residue left in the bore was pure carbon,; also SINCE THE BURNING TEMPERATURE WAS ABOUT THE SAME AS THAT OF BLACK POWDER, IT DID NOT ERODE THE BULLET SEAT OR BORE."

The book goes on to report that the Dupont powder that replaced No. 1 (Schuetzen Smokeless) was even more useful and successful used alone or as a priming powder in duplex loads. Steve Garbe has also written on the topic in his BPCN magazine.

So, unless someone can come up with with something to refute this, I regard the opposition to duplex loads as another of those "...everyone knows..." gun myths based on...? Strange how those that actually use duplex loads like them while the 'experts' that don't pan them.

When I first began duplexing, I was advised to prevent mixing of the smokeless and BP by compression, negating the use of a separation wad of any kind. I do this, compressing as I would for a 100% BP load.

Junkman:
PJ, I was not refuting your duplex loading. I wanted to know what the purpose was and you provided me with the answer. Now I know. Good luck with your experiments and please inform us how it goes. ;)

Lumpy Grits:
Duplexing is the answer to a question yet to be asked ;D

When the smokeless goes off, which is must faster burn than any BP, you are trying to push everydangthing else in that case before the much slower burning BP lights off. That is why you see a bulge in the case head after a few loadings that is a PITA to size down.

Your correct in it's your gun and do as you please.

I for one mhave to much time and $$$ into my Shiloh's to do something this "off" and unneeded.

PJ Hardtack:
I've heard the same argument re: using mag primers in BPCR reloading. I had some mag primers that I started to use up in my 50-70 loads and found no advantage I was aware of. The argument was that the hotter ignition would do what you described - push the compressed charge ahead causing problems; especially in heavily compressed loads with long powder columns.

If it did, you couldn't prove it by me, but I've only used mag primers in 50- 70 with no issues. Garbe's experimentation led him to believe that a 'cooler' primer was actually better for igniting BP. It isn't that hard to ignite. What matters is consistency.

I'm not experiencing the case head bulging that you mention. Makes me wonder what you were doing, or are you just passing on anecdotal information? As for any aspect of duplexing being a PITA, when you are acquiring lead, casting/sizing/lubing, sizing/depriming/annealing/cleaning/trimming brass, weighing/measuring/drop tubing/compressing powder charges ..... what's one more step in the process? It's already labour intensive.

As for duplexing being "off", give me chapter and verse to support your claim - like I did. As for it being "unneeded", that's your opinion. The reason it's banned in BPCR silhouette matches is that there is no way to regulate or prove the loads. Regrettably, people cannot be relied upon to be honest, ethical or safe, hence the prohibition of duplexing.

I suggest that if it was safe and accurate enough for turn-of-the-century riflemen, it is still so today.

Lumpy Grits:
I have had my best loads with LR match primers. (Fed or CCI)

What I related to you was "first-hand" with "eyes-on" helping other BPCR folks at the range. None of them duplex now, BTW.

I will never duplex with what I have seen. No need/want to.