Author Topic: Duplex loads (Read 1486 times)

gazz · « **on:** November 25, 2005, 09:21:12 PM »

Hi,
Some guys I know are into adding a bit of smokless powder into their black powder loads in the assumption that it will give more even burning and less fouling.It sounds just a wee bit too flaming dangerous to me!
Have any of you guys encountered this practice and do you have any horror tales to tell?
Cheers,
gazz.

dodd3 · « **Reply #1 on:** November 26, 2005, 04:38:46 AM »

gazz i use to do it but don't any more found it to erratic. i just use fff now it burns cleaner than ff and i get a bit more velocity.
bernie

Gatofeo · « **Reply #2 on:** November 26, 2005, 09:41:23 AM »

It has long been a practice to add a wee bit of smokeless powder next to the primer, before adding the black powder. This was done to reduce fouling.
Typically it was done in large-bore cartridge guns that held a lot of powder, such as the .45-70 or .38-55.
However, I can't recommend it. Before World War II, people were doing this and using bulk shotgun powder. Today, many of the powders used are long gone. Some shooters also used quick-burning powders such as Unique and Bullseye but I surely don't recommend this!
To my knowledge, the use of ANY amount of smokeless powder in black powder is forbidden in black powder cartridge rifle competition. It will get you disqualified or permanently banned from competition.
Then there's the know-it-alls who use small doses of smokeless powder in their muzzleloading rifles and cap and ball revolvers, before adding black powder. These types often end up wearing a puzzled look, standing at the entry to the ER or the Pearly Gates.
Under no circumstances should you use any amount of smokeless powder in a black powder firearm not designed for smokeless powder. And a pox on Savage for introducing that abomination --- a muzzleloading rifle that shoots smokeless powder. For that, they should get a cancer! :twisted:
In strong cartridge guns --- such as the Marlin 95, Ruger No. 1, Browning or Winchester 1885 --- you should be able to get by with adding a bit of bulk powder but what's the point?
After all, you still have to clean the cases and bore thoroughly after use.
As for shooting cleaner, if you can't get a black powder rifle to shoot halfway clean then you need to change your loading technique, powder, bullet alloy, bullet lubricant, bullet size and a host of other variables.
I find that in my .45-70 Trapdoor, I get clean loads by using Goex FFG, a greased felt wad on the powder, a soft lead bullet sized to .459 inch and a home-brew lubricant (search my name, I've listed the recipe ad nauseum in here and elsewhere).
I've never found the need to add smokeless powder to my black powder loads.
Frankly, the whole practice makes me nervous. More than a few guns have been blown up because the loader didn't realize he charged the case two or three times with a smidgen of smokeless powder, before seating black powder.
It's very easy to do: 4 or 5 grains at the bottom of a long, .45-caliber rifle case doesn't look different from 8 to 10 grains or more.
Id' steer clear of the practice.

sharps4590 · « **Reply #3 on:** November 27, 2005, 01:24:47 PM »

It has been done safely for generations and I have been doing it successfully and safely for well over ten years. I have no horror stories to tell nor do I know of any horror stories any of my many friends who have or do duplex can tell. Those who condemn the practice nearly always have no experience and precious little knowledge with duplex loads, as those on this thread have confessed. A little knowledge can be a dangerous thing......so can a lot of ignorance....and that is directed at no one.....the two sayings are inclusive.

Duplexing loads has it's place and use, muzzleloaders are definitely NOT one of those places in my opinion. I've never duplexed a muzzleloader nor do I ever intend to and I concur with the poster who shamed Savage for introducing a smokeless ML. I believe it was poor judgement on their part. Duplexing is also completely wrong and totally unethical for use in balck powder cartridge matches where either black powder or replica powders are required. Kinda smacks of poor sportsmanship.

In duplexing a load you aren't trying to "get by" anything or trying to slip something past the parameters of safety or the firearms ability. You are trying to improve a load in regards to accuracy, velocity, cleaner burning, every one of which duplexing achieves, and more! Sometimes duplexing is the only way one or all the above can be reached, depending on the firearm being loaded for. I have one rifle which falls into that category. Detractors can say otherwise but duplexing is quite simply the only way this rifle will shoot accurately. The reason it won't shoot accurately without duplexing is due to a combination of velocity and fouling. Now detractors can figure out what type of rifle it is.....maybe.

There are several powders out there completely adequate and safe for use in duplex loads. If you're interested in them do some research on your own as there is lots to learn and it won't be learned in a 10 minute search on a gun site. However, it is generally faster burning powders that are suitable.

Having said that I absolutely do not believe and must emphasize that duplexing is not for new and/or inexperienced reloaders. One must pay strict attention to detail or you are going to have a disaster on......or in.......your hands. One could say the same thing about driving a vehicle or shooting any firearm or operating nearly any piece of machinery on a farm or in a factory. If a person thinks they just tinkle a "wee bit of smokeless" in the bottom of a black powder cartridge case they probably shouldn't be playing with guns in the first place. There are volumes written on the subject complete with pressure tested loads and formulae. I reiterate that it can be done with no more attendant danger than conventional reloading of smokeless or black opowder cartridges IF ONE PAYS ATTENTION TO DETAIL!!!!!!

I'm not a particular fan of duplexing any more than I'm a detractor of it. I use the method as the means to an end. I'm glad I read and learned what I have and have had the opportunity to put the method to experiment and use. It is not the bugaboo it's made out to be.

Vic

Ray Newman · « **Reply #4 on:** November 27, 2005, 07:05:40 PM »

Sharps4590: well said!

cooper · « **Reply #5 on:** November 28, 2005, 02:42:36 AM »

I started using duplex loads in a 40/65 to try to get a high muzzle velocity (1300 1350 fps) for 1,000 yd. match shooting. I was able to do it, using 4 to 6 grains of smokeless, but my extreme spreads became huge 50 to 75 fps over 10-shot strings. That defeats the purpose of developing an accurate LR load.

However, some of my friends at the range have been able to make duplex loads with small spreads in velocity. Ive seen them do it, over a chronograph.

When I started using Swiss 3Fg, I could get MV of 1310 fps, so my need for duplexing went away. But I still think it has 3 uses:

The first is for hunting, where you can get a higher MV, along with a load that you dont have to blow tube (if you happen to need to take a lot of shots!) and which is also a bit easier to clean-up when youre done shooting.

The second is for an offhand load, where allowed. I dont like to blow-tube from the standing position. Trying to hold the rifle, and blow-tube, seems to tire-out my arms, and I think it affects my shooting. So Ive developed an accurate duplex load (at least for shorter ranges).

BTW duplexing is prohibited in SILHOUETTE, but I think it is expressly permitted in NRA long range. Also most gong-type matches (like Quigley) allow it.

Third, sometimes you just might have a bullet that wont shoot any other way! The 300 gr RCBS bullet is like that in both my 40/65 and my 40/70 Straight. The ONLY loads that will shoot that bullet, in either gun, are duplex. I have been unable to get that bullet to shoot, at the same, or higher, or lower, velocities, using straight black. But Im still working on it.

gazz · « **Reply #6 on:** November 28, 2005, 09:27:59 AM »

Vic,
Thanks for showing us the other side of the arguement. Could you please quote some of the references that you alluded to so we could arrive at a better informed judgement.
The way I have seen it done owes more to witchcraft than science, and that is what worries me.
Thanks,
gazz.

Ray Newman · « **Reply #7 on:** November 28, 2005, 01:18:37 PM »

gazz: how have you seen duplex loads fabricated that is so akin to witchcraft?

Off & on, Ive duplexed my BP loads, using SR4759 as the priming charge. I shot a great deal of it when I had a Browning B78, .45-2.1 as that was to be a hunting rifle.

For some threads on duplex loads, see:

http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=12680&highlight=duplex

http://www.shilohrifle.com/forums/viewtopic.php?t=4789&highlight=duplex

http://www.shilohrifle.com/forums/viewtopic.php?t=3901&highlight=duplex

Also, Gerald O. Klever, 100 Years of Shooters and Gunmakers of Single Shot rifles, pp10-12

As an aside, when White/Nitro (AKA Smokeless) powder was introduced, may Shooters made a duplex charge of BP igniting the White Powder as the BP was easier to ignite.

I've got the feeling that ShortStake is soon going to plug on this thread....

sharps4590 · « **Reply #8 on:** November 29, 2005, 12:49:19 PM »

Without digging thru the books in my library I'm able to give only one off the top of my head. "Shooting the British Double Rifle" by Graeme Wright. That's the one I've used most recently and that's been 3-5 years ago. His loads were pressure tested by both Kynoch and Birmingham Proof House. I am in no position to argue with their results.

Keith wrote quite a bit on it over the years. Several of the powders he used will obviously be dated but the method is the same. I'm pretty sure Seyfried has written some on duplex loads in The Double Gun Journal, but don't quote me on that one. I have a lot of respect for Ross and would love to meet him some day. He works with a lot of rifles I can only dream about. I apologize for not being able to be more specific at the moment. If time allows I'll happily list my other sources as I come across them.

It really isn't magic or witchcraft. Most of what I've read has stated no more than 10% of the charge should be smokeless. You reduce your black powder charge by an amount equal to a ratio.......and I don't have the ratio on the tip of my tongue. Maybe Ray does or I can look it up. Those same authorities generally also say to use the least amount necessary. On my one rifle that will not shoot anything else accurately the percentage of the smokeless charge is real close to 7%.

Ray said he used SR4759 and that has become my powder of choice for duplexing. I've tried 2400 and IMR4227 but SR4759 was always the best of the three in my shooting.

I'm not familiar with the threads Ray listed but I will take the time to peruse them before long.

If one is concerned or frightened by the practice then it would be best to avoid it, but it is a concern not based on fact.

Vic

ShortStake · « **Reply #9 on:** November 29, 2005, 03:37:12 PM »

Gents,

Ray has alluded to "pulling the plug" on this thread.

Please refer to the top most "Sticky" on this page.

Discussions pertinent to loading Black Powder Cartridges for use in Black Powder Cartridge Rifles with Duplex (smokeless powder) loads is a subject that both Graybeard and myself have agreed will not be condoned on this particular forum.

This particular thread should be, has been and is educational for those that do not possess a well stocked library of reference materials.

As long as SPECIFIC data for SPECIFIC Black Powder Cartridges are NOT a part of this on going discussion the post(s) will remain.

Ray Newman · « **Reply #10 on:** November 29, 2005, 08:02:27 PM »

I prefer SR4759 because being bulky, it takes up more room in the case. Problem: finding it. Dealers don't usually have it as it is a slow seller. I buy it in 5# containers. It is usually packed in 8oz. cans.

Per the IMR web site: "SR 4759. This bulky handgun powder works great in the magnums, but really shines as a reduced load propellant for rifle cartridges. It's large grain size gives good loading density for reduced loads, enhancing velocity uniformity." http://www.imrpowder.com/sr4759.html

Being on the cautious side, I also start out w/ a 5% charge of White/Nitro powder as the priming charge.

If you're going to duplex, @ one time Ideal/Lyman made a Duplex Powder Measure, the No. 5 IIRC. Look around for one as it is a handy device once you get it set up & working. Other made a duplex measure, but they are few & far between w/ a price to match. Or a dedicated pistol powder measure would also work. Saves time from switching between & re-calibrating the measures.

When I loaded duplex, I 1st dropped the White/Nitro, then immediately after, dropped in the BP, & compressed powder & wad. This way, I was sure that the correct amt'. of White/Nitro & BP were in the case. Very hard to double charge doing it this way.

Duplex loads will not overcome a poor lube, wrong bullet alloy or dia. It is not a panacea.

ShortStake made a valid point 'bout having a reference library. Over the yrs, I've managed to collect a few of the old Lyman reloading manuals & cast Bullet handbooks & a few reprints of them. Wealth of information in those tomes. When ever my local dealer got of box of old reloading equipment to sell or there was a tailgate sale of a deceased Shooter's gear @ the range, I went thru it. Most of the reloading books are usually overlooked, tossed or given away, or sold cheaply if there is no interest. A great reference work is Phil Sharpes Complete Guide to Handloading. It is also well-worth having Ned Roberts books, & those by Gerald Kelver. Sometimes these books can also be found @ flea markets & gun shows.