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'Duplex Loads'

Discussion in 'Handloading and Reloading' started by Oyeboten, Nov 15, 2009.

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  1. Oyeboten

    Oyeboten Member

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    I understand 'Lyman' at one time, made Bench Mount Powder Measure-dispensers, having two simultaneous acting resevoirs and adjustable measurering-dispensers, for use in Cartridge re-Loading, which dispensed Black Powder and Smokeless at the same time, for a combined Load.

    And, that in Hand Loading, using a small amount of Smokeless under a Black Powder Charge, was quite popular to do.


    Anyone here have any experience with this?
     
  2. azyogi

    azyogi Member

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    I'll use a small FFFFg charge [4-6 grs] under a pyrodex charge in my renagade .50 along with magnum #11 caps makes my load more reliable. but i think you were asking about cartridge loads
     
  3. Sunray

    Sunray Member

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    "...was quite popular to do..." By whom and when? Mixing BP with smokeless is asking for trouble. Massively different burn rates to start with.
     
  4. nicholst55

    nicholst55 Member

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    Lyman used to publish data for using a small charge of a specific smokeless powder as an 'igniting charge' for large volumes of BP. They have since discontinued the practice, and to my knowledge, only a few diehard BPCR competitors still do this.

    I understand that this significantly reduces the amount of fouling left by the BP. I suppose that if you felt compelled to try this, you could hunt up an old Lyman Cast Bullet Manual or Reloading Handbook that contains the data. I don't see a lot of point in it myself, but then I'm not shooting BP silhouette competition. I can stop and swab my bore between shot strings if I feel the need.
     
  5. Oyeboten

    Oyeboten Member

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    Initially, I was wondering about the conjecture, that 'Buffalo Bore' uses a blend or combination of Powders...


    Which led me to wonder on what History, if any may exist, for success in combining Smokeless Powders...


    Then I happened to run across a Mention in passing, then a few Paragraphs in an older Lyman Cast Bullet Booklet about 'Duplex' Loads of BP, and ('early') Smokeless.



    Interesting...
     
  6. MMCSRET

    MMCSRET Member

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    Duplex loads, and even triplex loads were used. I have used duplex loads for BPC rifles. 5 grains of unique first and 60 gr. of black sure makes clean up easier. I haven't found any reference in Lyman manuals but the Ideal Handbooks had them. Also Paul Mathews has a little to say about duplex loads in the older cartridges.
    Dick Casull used duplex smokeless over smokeless in the early days when he was working on horse powering up the 45 Colt leading to the development of the 454 Casull.
    Its not all black magic!!!!!!!!!!!!!
     
  7. Steve Marshall

    Steve Marshall Member

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    Duplex loadings helped make the transition from black to smokeless powder. Also experimenters such as Elmer Keith tried to improve ballistics. There were duplex powder .22's. I believe there was even a duplex powder. Some of these things seem antiquated today but they helped us get to where we are. Keith even experimented with front ignition, which was installing a tube inside the cartridge for the primer blast to ignite.
     
  8. Offfhand

    Offfhand Member

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    Nothing new or unusual about front ignition, as recently a a dozen years ago several experimenters, including myself, had converted cases to front (Tube) ignition for long range target shooting. Some with duplex smokeless powder loads. I think everyone decided that the minimal benefits were't worth the trouble. I certainly gave up on it as being too much trouble preparing the cases. However, I wouldn't be surprised to see someone trying it again with short magnum cases, and some of the newer propellents are more adaptable to duplex loads than those I experimented with. Triplex anyone? It's been done.
     
  9. Oyeboten

    Oyeboten Member

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    Front Ignition does sound like it would have merit...but, yes, particulars of Powder(s) and Bullet and Arm I'd imagine would play important roles in whether any merit is realized.


    Indeed...I did a few 'gogles' before hitting the hay last night, and found a few mentions of Elmer Kieth and his experiments...also, 'Casull'.


    Loading/reloading, is such a broad, deep and fascinating subject...endless..!


    Since I am presently limiting myself to Black Powder, or, it's 'substitutes', and, only for .38 Special.


    As an intermediary step on the path to 'Smokeless'...I will try some 'Duplex' Loadings, and see what I can find out.


    I have a Chronograph...


    So far, with slightly reduced BP load of 20.7 Grains of 'GOEX' (oweing to both how the modern Cases are of a little less capacity, and, my use of an .040 thick Grease-Wad between Powder and Bullet ) the average FPS, from my 3 inch Barrel S&W Model 10, 158 Grain Lead Semi Wadcutter, is about 710 FPS.

    And, abut 810 average, with my 5 inch Barrel Model 1902.


    A graduated series of prudently portioned 'Duplex' Loads, will be interesting to try, and, to see what changes occur in the FPS...the recoil, and, the report.


    I have a nice Scale now...with test Weights of 1/10th Grain and up...


    I tested the Scale with one, 1/10th Grain Weight, and, the Balnce Arm indeed was registering it nicely.
     
    Last edited: Nov 15, 2009
  10. Jim Watson

    Jim Watson Member

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    As said the old time scheutzen shooters had double hopper powder measures that would dispense say five grains of the old bulk smokeless, then 35 grains of black into a .32-40. This gave a clean burn without boosting the pressure or velocity enough to hurt accuracy, which was their only objective.

    Some modern scheutzen shooters still use duplex loads with 5 to 10% of smokeless - Reloder 7 is popular - under their black powder main charge in .32-40 or similar.

    The NRA used to allow duplex loading in BPCR target shooting but I think they have disallowed it now, limiting you to straight black or Pyrodex, no other fakes or combinations.

    I have an article with pictures of a demolished Remington Rolling Block that was thought to have been loaded reverse duplex, five grains of black, 50 grains of smokeless. Y'all be careful, now, you hear?

    I would not know where to begin with a pistol caliber.
     
  11. Oyeboten

    Oyeboten Member

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    Thanks Jim...


    I'll brood a while...then decide what Smokeless to try.


    I'll be methodical and careful...you bet...


    Wish I had a way to test for actual PSI.


    Be nice if there was a way to out fit an old .357 with a tapped-on piezoelectric device...
     
  12. evan price

    evan price Member

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    Once upon a time I used to know little about reloading but I hammered together rounds using a very slow surplus powder and the only way to get good brun was to touch it off with a fast burning rifle powder put into the case before the slow powder. THis worked. It's also a good way to blow your hands off if you miscalculate. I was playing with fire back then and never again.
     
  13. ArchAngelCD

    ArchAngelCD Member

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    I agree, when you play with fire you will eventually get burned.

    With all the great BP Substitutes around today why would you even think about doing this? (other than to say you can) The "modern" substitutes burn clean and reliably. Even the caps are made better and Magnum caps are available.

    If you are looking for something that burns hot and clean give IMR White Hots a try.

    BTW, I own a Lyman (Ideal) Handbook No.39 (May 1953) and I don't remember seeing data for Duplex loads in it. If it is there I didn't notice because I wasn't really looking for it. If I can dig it out this week I'll look it over and let you know if "Ideal" listed duplex data in their 1953 load manual or not.
     
  14. Oyeboten

    Oyeboten Member

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    Hi ArchAngelCD,



    For the time being, I am only Loading for .38 Special, Revolver...in Black Powder, and, trying various of the so-called 'substitutes', also.


    I am being fairly meticulous, far as that goes...and, keeping Records, testing with a Chronograph for FPS.


    I'm not suggesting FPS is any indicator of Pressures...just saying I'm working with what I have.


    'White Hots' appear to be 50 Caliber 'sticks' intended for Rifles...I'd have to grind them up in my Coffee Grinder for converting them into Powder for .38 Special Cartridges for Revolver...and, grinding them into fine Powder might effect their flame-propagation-properties 'up', or, 'down'...but probably 'up'.


    Hey...might work Great...I dunno...but, I'd go easy and work 'up' if I was going to try it.


    I'm just curious about things...that's all...no other 'Reason', other than interest...curiousity...an interest to try things.


    I'm interested in trying different Smokeless Powders eventually...and 'Duplex' BP/Smokeless, between now and then.


    I'll be careful...



    The "Ideal No. 6 Universal Powder Measure" I think is one which had tandem or Parallel-Twin Hoppers...and each had their own metering Valve-Tumblers...for dispensing pre-determined BP and Smokeless into the same Cartridge.


    I assume one operated the BP half, then the Smokeless half...in that order.


    Probably 1953 is too recent...for any but passing mention, if even any, of BP based Duplex Loadings.
     
    Last edited: Nov 16, 2009
  15. qajaq59

    qajaq59 Member

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    Please do.
    I'm still wondering though why you would want to mix powders. What would the benefits be that might offset the dangers?
     
  16. Afy

    Afy Member

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    Just use Swiss fffg and be done with it. It is excellent BP and fairly clean as far as BP goes.
     
  17. ChristopherG

    ChristopherG Member

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    Oyeboten, it sounds like you have a real interest in both safety and the historical development of reloading, both of which we can all applaud. However, I think the PERSONAL progression you have in mind is a bit cart-before-horse in terms of both these goals.

    In historical terms: When smokeless powder came along in cartridges like the .38 (and it's a great cartridge to do all this with), people did not BEGIN by dicking around mixing it with BP--they REPLACED BP with smokeless and thoroughly explored the potential of the smokeless powders available to them. The mixed/duplex loads were a subsequent and minor development, an attempted refinement.

    In terms of safety: modern smokeless powders are wonderfully consistent, thoroughly researched, and easy to work with. Of course they require care, but they are used all the time by grillions of people who still manage to count to ten without resorting to taking off their socks. Duplex loads? Again, they're an esoteric, specialized branch; nobody STARTS their smokeless reloading with Duplex loads, for good reasons. They are poorly documented and understood.

    So from both historical and safety perspectives, I'd suggest you do some smokeless reloading before you start mixing smokeless and BP or mixing different smokeless powders. If you want to keep it historical, start with Bullseye, which is as old as commercial smokeless powder gets. You may find that, with all the smokeless options that have been developed, Duplex loads have remained a small historical cul-de-sac for good reason; modern smokeless powders can do anything in a .38, from gallery loads to Keiths.

    Hope I haven't misread your interest or intentions.
     
  18. Jim Watson

    Jim Watson Member

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    See there, your assumptions are already setting you up for trouble.
    A duplex load is prepared with the smokeless in first down over the primer, THEN the black.
     
  19. griz

    griz Member

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    First, duplex loads are not mixed powders, they are two different powder speeds stacked one on top of the other. They must be compressed by the bullet to keep the two from mixing.

    Some folks tried duplex smokeless loads to try and get more velocity without higher peak pressure. The theory was the slower powder would start the bullet, and about the time the pressure curve was dropping (the bullet was traveling too fast for the powder to accelerate it any more) the fast powder at the top of the powder column would give it another kick.

    As you can imagine there were a lot of variables to juggle around. Combine the fact that the people who tried it first no longer use the method, and considering that there are so many well suited powder choices now for any application, duplex loads seem to be an idea whose time has passed.
     
  20. qajaq59

    qajaq59 Member

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    That seems to be the concensus in anything I've ever read on it. But I'm sure there us still someone somewhere trying it. There always is when it comes to reloading.
     
  21. Otto

    Otto Member

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  22. Oyeboten

    Oyeboten Member

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    Hi ChristophrG


    You'd mentioned -




    Very well said...


    My thought...was to elect a fairly Slow Powder which is documented for use in .38 Special Loadings...research 'normal' 148 Grain Full Wadcutter Loadings for .38 Special with it...allow one/fifth of it's usual amount when for mid range Target Loadings, and, reduce BP by 1/4 or even 1/3rd...seat Bullet to light compression...see FPS and other behavior.


    Possibly this is imprudent...even at these Loadings...but such was my tentative thought/plan/notion.


    If this truly does seem unwise or dangerous, I will abort Mission and by-pass indulging in 'Duplex' curiousities.


    I understand my safe 'ceiling' for the Model 10, is in the higher-mid teens of PSI.


    Having no way to really caclulate synergistic propagations, I understand, that 'Duplex' is largely unknown, possibly unknowable without sophisticated Test Equipment, as for the resultant pressures one is actually going to get, other than, that by proportion of the respective powders, one is welcome to guess.


    Certainly any 'Pressure Signs', of flattening Primers or Case Heads, would not not need to even be present for the pressures to have already exeded the Model 10's ceiling.


    So...yes...your courteous concerns are not in vain...nor lost on my mental-models of events...and imagination..!
     
  23. Oyeboten

    Oyeboten Member

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    Hi JimWatson,



    I had mis-spoke somehow.



    It has been clear to me from the get-go that in the old 'Duplex' Loadings, the Smokeless goes in first, aginst the Primer, and, the BP follows, 2nd.

    ...sorry...Lol...


    Thanks for pointing out my flub...
     
  24. Oyeboten

    Oyeboten Member

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    Hi griz,


    You'd said -



    Yes...this sums up my appreciation...and, some of my gradually evolving prospective long term intent -

    More effecient pressure curve...higher FPS at safe pressures, no nasty 'spikes'.
     
  25. Oyeboten

    Oyeboten Member

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    Hi Otto,



    Sorry you feel that way about this...
     
    Last edited: Nov 17, 2009
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