beginner's duplexing questions (45-70)

[ksJoe]

I've spent several hours reading all the threads I can find about duplexing the milsurplus 50 BMG powders, such as WC867, WC872. Here's the questions I'm coming up with.

I've not found official load data, which makes me a little nervous. I've seen comments that old Lyman manuals have some duplex loads in them, but I get the impression these are black powder duplex loads. Is this correct?

So you basically start with 2-3 grains of kicker powder, and fill the remaining capacity with enough slow powder to get slight compression. Then gradually increase the kicker powder (and reduce the slow) until it shoots cleanly. The rough ratio of kicker powder is 10%, and depending on the kicker selected, somewhere over 10% / 6 grains might start causing a problem. Is this correct?

Compared to my other reloading experience, this seems extremely lax. I've seen comments that straight wall cases (e.g. 45-70) cannot generate enough pressure with the 50 BMG powders to be a problem (but too much kicker powder can pose a problem). So I guess that might explain the lax procedure?

I've not seen comments about these duplex loads in old trap door 45-70s. Are they safe in these guns?

Other things I've picked up:
RL7 was suggested as a less sensitive kicker powder.
Magnum primers are preferred.

So do I have this about right, or am I fixing to blow myself up?

Thanks guys!

[redneckdan]

You got the gist of it. I am not certain that these loads are trap door safe. I wouldn't chance it. My loads were kicking a 450gr bullet out a 1600. Seems a little hotter that data listed for the trap door. If you load too much kicker it is possible to get an over pressure event, the WC860 would act more as a filler in that case. I have gone all the way up to 10gr of red dot with a case full of 860 and had no pressure problems, slight increase in velocity but nothing to indicate problems. I have settled on 5gr as my universal kicker charge for most cases having a capacity of 50gr of 860 or more. Going with a slower (relative to the red dot) rifle powder for the kicker will reduce the chances of over pressure. I have never needed magnum primers.

[ksJoe]

I thought of another question: Do these loads work ok in 18.5" barrels?

Thanks,
Joe

[redneckdan]

sure. I have used them in everything from a 32" buffalo classic to a 18" marlin. You will get more bark and muzzle flash with the short barrel but it will still work

[9.3X62AL]

45-70, in a Ruger #1.....6.0 grains of IMR-4198, then 48.0 grains of WC-860 in Rem cases gives 100% load density using the Lee 405 grain boolit seated to kiss the leade. Winchester cases hold 2.0 more grains of WC-860. This cleans up the WC-860 granules in the bore, and gives 1300-1325 FPS with EXCELLENT accuracy. I use Federal 215 (Large Rifle Magnum) primers. I couldn't say whether this load is Trapdoor-safe or not, but its resulting velocity is in the Trapdoor toll-free dialing area.

[Shiloh]

Is this something you really want to do??

What do you think about acquiring the correct powder for your specific need??

Shiloh

[SciFiJim]

Is this something you really want to do??

What do you think about acquiring the correct powder for your specific need??

Shiloh


I've thought about working with duplex loads as well. If it was just acquiring the right tool for the job, I would just shoot commercially loaded ammo. It's about exploring new areas. Asking for advice here is about trying to explore those areas safely.

[turbo1889]

My main piece of advice to you would not to think of it as duplexing loading. Rather think of it as that you are just trying to "boosting and extending (emphasis on extending) your primer burn and making your ignition cycle more reliable and stable". In reality that is all you are really doing if you are just using a few grains of faster burning easy igniting powder in the bottom of the case directly over the primer and filling the rest of the case up with a slow burning hard to ignite powder.

It also keeps you balanced, if you are already beyond three or four grains and you aren’t getting the desired effect then you best just stop right there since the idea isn’t to use the faster burning powder as a propellant at all. It is just the dry kindling used to get the big logs burning in your campfire and if you put in too much kindling you won’t have a campfire you will have a forest fire on your hands.

Try to get your hands on a 50-BMG primer and set it next to a regular large rifle primer. The things are huge compared to a regular primer and that is what 50-BMG powder is made to be ignited with.

Just boost and extend (emphasis on extend) your primer burn enough to provide reliable and stable ignition that is all you need or want to do.

As to whether such loads will be trapdoor safe. Well the now discontinued Accurate 8700 powder which was basically the same thing as 50-BMG ball powder only easier to ignite was used in 45-70 load data in the form of full case compressed loads. Their load data charts from back before that powder was discontinued showed that kind of load using that powder with 340 to 530 grain lead boolits using charges between 49.5 & 65.0 grains producing pressure levels between 9,800 & 15,900 PSI that are listed in the trap-door load section. Of considerable note, however, is the fact that these were loads that did not have a primer ignition booster charge but were just straight AA-8700 powder as full case compressed loads. In my personal experience AA-8700 was easier to ignite then the mil. surp. 50-BMG burn rate powders I have used. I cannot, however, guarantee that this means that your going to get the same low pressure levels using the mil. surp. 50-BMG burn rate powders with the addition of a primer ignition booster charge.

[ksJoe]

Asking for advice here is about trying to explore those areas safely.

Yup.

So it sounds like I'll not be shooting these loads in a trap door. I don't have one, but Dad does. If there was unanimous agreement here I'd think about it.

I actually have several powders that are "correct" for 45/70. But I make different kinds of loads for different purposes. For hunting loads, I don't care about the cost. For plinking, I'd like it as cheap as possible. I find that the more the rounds cost, the less fun it is to go play at the range (regardless of what I can "afford").

I ordered brass a couple days ago. Now I just need to find a deal on a 1895SBL.

Thanks guys!

[SciFiJim]

Rather think of it as that you are just trying to "boosting and extending (emphasis on extending) your primer burn and making your ignition cycle more reliable and stable".

This has been my thought on "duplexing" for as long as I have been studying the process.

The idea as I understand it, it to start with a full case of the slow milsurp power as a baseline. You will have unburned power left over on firing. Then starting with ONE grain of a faster power next to the primer as a kicker, work up loads one grain at a time until you get complete burn. If you start approaching 10% of the loading with the kicker and you still don't have complete burn, then stop and rethink what you are doing. You might need to change the starting power and rework the loads.

[Larry Gibson]

ksJoe

I'll suggest you stick with "correct" powders for the TD, just not enough margin for error in that old rifle.....I learned that the hard way.

Also consider the false economy of using milsurp powders that cost 1/3 - 1/2 as much as with a "correct" powder; In reality you end up using at least twice as much of the milsurp powder plus the expense of the "kicker" powder so the cost per shot is essentially the same as if you used a "correct" powder.

Larry Gibson

[SciFiJim]

Also consider the false economy of using milsurp powders that cost 1/3 - 1/2 as much as with a "correct" powder; In reality you end up using at least twice as much of the milsurp powder plus the expense of the "kicker" powder so the cost per shot is essentially the same as if you used a "correct" powder.


This is why to this point I have not used duplex loads. However, the idea is still intriguing and more knowledge is better than less. If some time in the future I run across a screaming deal on milsurp powder I can get it knowing that I have a way to use it instead of passing on it because I don't have a use for it.

[Jim]

If the point I'm about to bring up has been made and I missed it, forgive me.

The thing that concerns me is, these old shoulder fired cannons weren't designed to stand the pressures of smokeless powders. I do realize that smokeless powders can and are used in low pressure firearms. however, if the pressures of duplexed loads eventually cause the rifle to fail, the failure is going to be catastrophic.
We've all seen photos of modern bolt rifles and revolvers that have failed and little to no injuries were experienced. I'd be scared to think what might happen if the action on a trap door failed.

[9.3X62AL]

Lotta good posts above. Regarding the use of WC-860......it made economic sense to use the powder in 45-70 when it was running $3-$4/pound a few years ago. Nowadays, not so much. It still has utility in over-bore-capacity rifle applications, but here again the cost savings are becoming small to non-existent as these 50 BMG and 20mm powders climb upward in price per pound.

[doubs43]

I've been using - very successfully - duplex loads in my 45-70 rifles for more than 20 years BUT I'm not advocating their use in a Trapdoor. My loads are accurate and have sufficient power to down a ram with a hit anywhere at 350 yards.

My 45-70 loads are: RCBS 300 grain GC boolit. (My mold drops them at 320 grains.) 3.0 grains of WW-231 OR 3.0 grains of Bullseye topped by 57.0 grains of WC-860. Velocity is 1600 fps. I have shot this load in at least 5 different rifles and all of them have liked it. It's also easy on brass.

A second 45-70 load that has performed well is the 405 grain Lyman plain base boolit with the WC-860 reduced to 56.0 grains.

Both loads are slightly compressed, require a light-moderate crimp and will leave a few unburned grains of powder in the bore. It doesn't effect accuracy at all.

In 6 Buffalo Stakes Matches this year at our local club, I've won 3 and placed second once. We shoot chickens at 100 (5 offhand), pigs at 150 (2 are very small), turkeys at 200 and rams at 350. This past Saturday, 2 chickens were used at 200 yards and 2 turkeys at 350 yards. I won the January match with a Pedersoli 1874 Sharps in 45-70 using a 300 grain SAECO plain base boolit in place of the RCBS GC boolit. The rest of the matches have been won with a Winchester Hi-Wall Traditional Hunter in 38-55.

I use identical powder loads in the 38-55 but with two different cases and two different boolits.

248 grain Lyman boolit sized .378" in a WW 2.080" case and an RCBS 312-BPS boolit sized the same in a Starline 2.125" case. The powder loads are 2.5 grains of WW-231 and 34.0 grains of WC-860. I use the Lyman boolit out to 200 yards and the RCBS boolit at 350 yards.

These loads have been good to me and I'm presently working with a 40-65 to find a good duplex load for it. The tapered case doesn't seem as easy to work with as the straight walled cases but I've found some promising loads that I need to fine tune. However. at the moment my best load is 30.0 grains of H-4895 and the Lyman 395 grain tapered boolit.

Anyone using the load data I've given above accepts full responsibility for the results. I have no control over anyone's reloading methods except my own.

[ksJoe]

The thing that concerns me is, these old shoulder fired cannons weren't designed to stand the pressures of smokeless powders. I do realize that smokeless powders can and are used in low pressure firearms. however, if the pressures of duplexed loads eventually cause the rifle to fail, the failure is going to be catastrophic.
We've all seen photos of modern bolt rifles and revolvers that have failed and little to no injuries were experienced. I'd be scared to think what might happen if the action on a trap door failed.

Understood. I won't be firing them in a trap door. If the opinion was unanimous that its safe, and people were lining up saying they've been doing in for dozens of years in dozens of trap doors, I'd think about it. But you guys' opinion is pretty much the opposite of that, so I'm not considering it.

I was surprised I couldn't find any info about using the smokeless duplex loads in a TD when I was googling. I found BP duplex discussions for TD, but not milsurplus powder loads. I was guessing the question had come up before, and if it was a problem I'd find talk about it.

Now when I google for duplex 45-70 trap door, this thread is the second result. So maybe that will help the next guy.

[ksJoe]

Also consider the false economy of using milsurp powders that cost 1/3 - 1/2 as much as with a "correct" powder; In reality you end up using at least twice as much of the milsurp powder plus the expense of the "kicker" powder so the cost per shot is essentially the same as if you used a "correct" powder.

That's a good point. I ran across the duplexing threads when I started looking for cheap load data. I was looking at published loads full charge type loads, that ran 15-18 cents a shot for powder. At that point duplex loads were looking like they could cut the cost by around 2/3.

Since then I found the "10 grs unique" sticky, and now the duplex loads don't look so cheap.

[BruceB]

Seems to me that the cost is over-stated.

For ease of claculation, let's say the main charge is seventy grains, or one hundred loads per pound. RIGHT NOW, today, we can buy WC867 or WC 872 (both slow-burning 870-type surplus powders) from Wideners at $49 for EIGHT pounds, or just over $6 per pound. Ergo, about six cents per round.

If we use $20 as a reasonable per-pound price for the kicker powder, a 3.5-grain kicker will cost ONE PENNY. A 7.0 k icker will cost TWO pennies. This is not big bucks, amigos. A full-power .45-70 will be about seven or eight cents for powder, and maybe two or three cents for a primer.

Not an earth-shaking expenditure, by any means.

[Montana Ron]

No one has brought up the most important issue with a DUPLEX loading.....Without compression
as in old black powder loads to keep the prime charge located in the right place you got Nothing but erratic results or worse compressing modern smokeless loads to the same degree one would
have to load black and prime loads...........They make good powder now, this isn't the 1800's and
this frugality can be your downfall.........................

[turbo1889]

Montana Ron does have a point about compression. All duplex (and triplex) loads are compressed loads. An absolute necessity to prevent powder migration in the load.

I think most of use that use duplex loads know this is how it is done and consider it to be a given. It’s worth stating though since a beginner might come along who doesn't know that.

I don't consider compression of a load to be an annoyance or a problem of any kind. In fact, I find compressed loads often provide more consistent ballistics even if we are talking about regular loading that doesn't involve any primer booster charges, surplus powders, and/or cast lead boolits. With regular jacketed bullet reloads in many cartridges using regular canister powders the loads listed in the loading books as compressed charges are often the best loads. Modern smokeless powder benefits from compressed loads too regardless of what year it is.

[doubs43]

In post #15, 4th paragraph, I state that my loads are slightly compressed. However, it's still a good idea to emphasize that smokeless duplex loads NEED to be compressed for best performance. As Turbo1889 comments, a compressed duplex load is likely to give more consistent ballistics than an uncompressed single powder load. My 45-70 loads give 10 fps average deviation.

In my experience, no matter the boolit weight, you can't possibly stuff enough WC-860 in a 45-70 or 38-55 case to generate excessive pressures. The only way you'll get high pressures is by using too much ignition powder. I find that 3.0 grains in a 45-70 & 40-65 or 2.5 grains in a 38-55 is enough to do the job. The only danger is a double charge of the fast powder. I'm very careful and double check to make sure I don't do that.

[mattbowen]

Okay;
I have a question I see everyone talking about WC-860. What is the difference between WC-860 and WC-872 and can WC-872 be used in place of WC-860?

Also I see that widener's also has WC-867, From the number I would think that this would be closer to WC-860 so would the loads be close enough to use?

Thanks

Matt

[Char-Gar]

Some years back when WC872 was really cheap, many of us played with it. It was developed for the 20mm Vulcan round.

In most applications for bottleneck cases it will burn OK with light compression. It produces outstanding accuracy in the 30-06 and like medium capacity rounds with cast bullets. You can't get enough power in the case to get you into troubles.

When it comes to straight cases like the 45-70 that is another matter. To get a decent burn it will require a kicker charge of medium powder like 3031 or something in that range. Stay away from ball powders that can mix with the slower ball powders.

Many of us have done it with no problems and good results. BUT we are dealing with the unknown here. There is only anecdotal data, none of which has been lab tested. Therefore I am very hinky about sending someone down that path.

I certainly would not shoot such loads in a Trapdoor Springfield or any other weak action. I don't think the pressure of such loads would be excessive, but nobody knows for certain, therefore best not to do it.

We have added many, many new members to this board since the days we freely exchanged data and out of the box experiences, and too many of those new members don't have good sense. l

[mattbowen]

Chargar;

Thanks I understand, what do you think about the WC-867?

[Longwood]

I am new to 45-70 shooting and am doing a lot of testing with different powders, different boolits - lubed and two different types of paper patched made from my homemade molds- and bullet metal formulas.
Can a powder as slow as 860 be cut back some?
I was told on another site that I can fill it to capacity or, as low as, 70%.
I know powders like 4227 can burn very erratically if you try that.
If I were to try it with 860 and 405 gr to 535 gr boolits, should I use a thin card wad over the powder and or filler and another card wad?
I am old and retired and only plink nowdays so I want to keep the price down so I can do it very often.

[redneckdan]

I have done so. On method is to seat the bullet deeper if possible. Another is to fill the space with something. I prefer cream of wheat. More biodegradable then card wads. One load I used was the lee 350gr bullet with 3.0gr of red dot and 35.0gr of WC860. Can't recall velocity off hand but it was much friendlier than the full snort loading. I have done the same thing with my .30-284 with similar results. Haven't tried it yet with my 375 H&H.

[Char-Gar]

mattbowen.. I have no experience with the powder you mentioned, so I don't have an opinion. Back when WC872 was so cheap, I bought 64 pounds of it and still have a bunch. Enough to last me for quite a while.

redneckdan... If there is still some space after I have put in the proper charge of WC872, I top it off with Precision Shotshell Buffer to get light compression. I am hinky about using natural fillers like cream of wheat, which have been known to take on moisture from the air. When that happens it can swell and push the bullet forward or turn into a hard plug. If you have a hard plug in a bottle neck case, that can cause a real pressure spike. These are the reasons I go with an inert non-organic substance like PSB.

The use of card wads can cause real problems if someone inadvertently leaves an air space between the wad and the bullet. The wad acts like a piston and compressing the air space and barrels can be bulged or worse.

[wiljen]

I've used the 1/2 inch vegetable wads in the 45-70 to reduce case capacity when using powders that dont like air space.

[Cap'n Morgan]

What kind of ES and DS variation are you guys getting with duplex loads?

[mattbowen]

Chargar;
Thanks for the reply. Is WC-872 as good as WC-860, I have read that some people have had problems with pressure spike in hot weather. I live in SC were it is all most always hot.

Thanks again

Matt

[Jim]

Matt, when I lived on James Island, I had a place to shoot down highway 17, just south of Ravenel. I know all about that heat and humidity.
One summer, I had been working on a new load and was getting some high pressure signs that should not have showed up. It was one of those 95* low country days. Come to find out, the ammo was getting hot.
Next trip, I put my ammo in trays and carried them in a cooler with a little ice in the bottom. I left the cooler top open but the ammo stayed in the trays in the bottom. The pressure signs went away and the load worked fine.

[mattbowen]

Jim I had that happen at the house when I was checking the zero on my 3006 last year, so I started shooting in the morning or afternoon.

Matt

[Jim]

There ya' go, Matt. 'Specially if ya' can find a nice shady spot, right?

Them nats and skeeters eatin' ya' up down there yet?:bigsmyl2:

[mattbowen]

I sprayed the yard yesterday evening to kill the unwanted ones

[frnkeore]

I don't know how relevant this data will be to this discussion but, here goes.....

This data is dated Feb of '90 in my chrono book.

The rifle is a 1878 Sharps Borchard, 31" lg Octagon Douglas barrel, 20 twist.

WW cases and F210 primers and a light foam wad against the powder.

Bullet is a NEI 430 gr spitzer cast 20/1.

1. My loads aren't compressed. They take up about 65% of the case capacity.

2. They are not fixed but, breech seated.

Load- 15.0 gr WW296 under 27.5 gr IMR4831
Velocity- 1473
Ex spread- 10 fps
SD- 4 fps
Accuracy for 5 shot group- .60 @ 100 yds

Increasing 2.5 gr 4831 and decreasing by the same wasn't as good.

I'm another advocate of 10 Unique, with that load (all other things the same) and no wad, I got ........

Velocity- 971 fps
Ex Spread- 19
SD- 6.9
5 shot Group- .84 @ 100 yds. 4 in .48

Frank

[grumman581]

A second 45-70 load that has performed well is the 405 grain Lyman plain base boolit with the WC-860 reduced to 56.0 grains.


What kind of velocity are your getting with that particular load?