Duplex loads?

[jonk]

Someone suggested that I might try a duplex load in loading the Trapdoor Springfield. Specifically, 7-9 gr of SR4759 and 50 gr of Goex CG. SPG lube or similar. (I have 2 sticks of Bullshop's black powder lube so I'll use that to start). I'm willing to give this a try but have never done a duplex load before. Any things to watch out for? I assume that my surplus 4759 would do fine, even if the granulation is slightly different from the factory stuff? I'm using a Lee 405 HB bullet so over powder wads and grease cookies are more or less out- though I could try filing the base of a few if the grooves don't soften fouling enough.

[Curtis44]

jonk, I would start with about 5.0 g 4759 and enough ffg or fg to allow a little compression. The HB is small enough you may be able to use a wad (or 2) anyway.

I did not have outstanding results in my trapdoor with the lee hb bullet however. My best results so far have been with the lyman 457483 with GC and sized .461. I put 2 .60 fiber wads over the powder and compress about .10" Shoots 2" groups @ 100yds if i do my part as long as the ammo holds out without cleaning. Alloy used is 1/20 tin/lead.

You will also find out that you will probably need a taller front sight to get her to hit at poa at 100 yds. A new sight can be easily made from hard sheet brass available fron K&S metals. File it to shape and blacken with birchwood Casey Brass Black. A small pin holds the blade in place. Of course, save the original sight blade to keep the collector types from picketing your house!

Curtis

[jonk]

:-D Lol. Yes, it does shoot high- I've found that to be the case already. For playing around I just use a target about 2 feet lower than the one I'm ACTUALLY shooting at.

I got the Lee mould first as it is so cheap- and well worth trying first. Plus the hollow base offered good prospects for obduration. I've got some vegetable fiber wads and some Thomson .45 felt wads. The felt didn't work but the fiber might.

One thing at at time though, first I'll try without wads.

The only problem I've run into is that sized to 461, the cases bulge even if I flare with an M die. I might try not resizing at all and using a roll crimp and see what I get.

[Boz330]

The only problem with a wad might be that it could get stuck in the base and cause a flyer. Leaving the brass unsized is the best approach. There is a taper crimp die available from Buffalo Arms that would probably give better accuracy than the roll crimp, but I would see how tight the fit is without anything. Thats what I do for BPCR.

Bob

[montana_charlie]

Someone suggested that I might try a duplex load in loading the Trapdoor Springfield.
Not knowing what the discussion was about when you received that suggestion, I wonder what your context is.
In other words, do you know where the advantage lies in duplex loads?
Have you been unsuccessful with the other methods of fouling control?
CM

[13Echo]

The Lee 405gr hb is a copy of the original 1873 45-70 bullet. I've had good luck in Springfields with 59grs FFg Goex compressed enough to seat the bullet to get a firm crimp over the front band. If you are using the usual sizing and expanding dies you may have trouble seating this bullet as it does run large in diameter (mine casts at .460 to .461") and most dies are set up for .457 bullets. You might have to get a custom expander from Buffalo Arms to properly load this bullet (about $18 as I recall). It is worthwhile for the trapdoor as most seem to need the larger diameter bullets. Mine won't group with .458" bullets but is accurate with .460". The 405gr bullet, at least in my rifles, also needs a good crimp. Apparently, at least the theory is, the bullet is too light to properly obturate unless it has the crimp. I don't use a wad with this bullet. The SAECO 500gr 1881 bullet seems to do fine with little or no crimp. At any rate I haven't found a need for duplex loads and prefer to avoid smokeless powders in these od soldiers.

Jerry Liles

[Curtis44]

Jonk, you might try the lee universal expander die to allow those .461 bullets to seat. a custom "M" type die would probably be better, but the lee seems to work just fine.

BTW the reason for using duplex loads is because they work (greatly reduce fouling) and ARE still historically accurate, just to a later time period that the buffalo runners. Most shooters of the tut=rn of the century years used smokeless "primers" in their black powder cartridges to reduce fouling just line we use whatever new tricks such as SPG lube, Walters wads, grease cookies, etc, etc to do the same thing.

IMO it is not reasonable to call the use of duplex loads "not authentic" unless you limit the time period of use from 1870 to 1895 or so. Many shooters were still using their BP rifles well into the 20th century, and many were using duplex loads.

An article in the 2005 gun digest by Harvey Pennington (page 34) quotes Col. Townsend Whelen discribing a six month hunting trip in British Columbia were Whelen hunted with a 40-72 Winchester M-95 and his partner hunted with a 38-55 Winchester m-94, each with cartridges loaded by Whelen "with black powder, smokeless priming and lead bullets"

[jonk]

It isn't a question of fouling control; just something new to try. Though fouling control is a nice side benefit.

I have tried a Lee universal flare die. It flares the mouth enough to start an unsized bullet in, yes, but said bullet still bulges the brass and does so irregularly, so it won't chamber much of the time. As I say, I may next try not sizing the case and just seating/crimping, with a flare before seating if needed. If that doesn't do it I will try getting a custom expander. They're lee dies and as I recall lee will do a custom expander at a reasonable price.

[Larry Gibson]

Jonk

Back the sizing die out until the inside of the case, when sized, is .460 if using .461+ bullets. Most dies will still taper the case toward the case mouth so with the Lee Univeral expander to flair the mouth you will get good bullet tension and not damage the bullet. The duplex load was recommended to control fouling, it blows it out the end of the barrel, which enhances accuracy becase you won't have to blow in the barrel nor clean the barrel after a few rounds. The duplex load was worked up using the suggestions of J. S. Wolf and may be found in his book; Loading Cartridges For The Original .45-70 Springfield Rifle and Carbine. As mentioned in a previous post duplex loads are not new and they have been in use for well over a century. A wad is not benificial when using the M1873 bullet as they do get stuck in the HB and cause flyers. This is why Frankford Arsenal stopped using the wad in the 45-55 load in the late 1870s. Bullshop's BP lube should work fine, just needs to be formulated for BP is all.

Larry Gibson

[jonk]

Update:

I tried unsized brass, the same bullet as cast, and a duplex load of 5 gr of SR 4759 with an FFG charge of 60 grains- enough to fill to bullet seat depth and allow for very light compression. I was wowed- previously the gun's best had been 6" at 50 yards; the duplex load, after one fouling shot, shot 2 five shot strings with all shots touching. That was all I loaded for the test- I'll certainly be loading more!

Thanks for the suggestion!

[Larry Gibson]

You're welcome, jonk.

Larry Gibson