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Duplexing Smokeless Powders

  1. PewProfessional89
    PewProfessional89
    I know there are people out there duplexing gunpowders. WC 860 and IMR 7383 are way to cheap to not try in smaller than recommended calibers. Hell, I've been doing it for a bit with the 300 Blackout. I have had luck with IMR 7383 over a kicker of BR-5 from gibrass.com using the lee 309-230-5r boolit. I am currently working up loads with the Lee 312-165-1R In the blackout as well. Is anyone else having any luck with this kind of stuff?
  2. MT Gianni
    MT Gianni
    I don't believe duplexing is the same as using a kicker charge which is what I do with 860/872 in the 06. I find 3-5 gr of a faster rifle powder like 4198 oe 3031 does wonders to get a good powder burn. The oddity I have seen with 7383 is how it behaves in different bore sizes. I may want a kicker in a 40+ cal rifle but not in a 8 mm or smaller one. I got a nice burn in the 356 Winchester before it was sold off. I have not yet played enough with it in the 358. I am of the opinion it prefers a slight case reduction to the bbl not a heavy case to neck reduction. For me on a non magnum case I think it has a lot of use from 7mm to 375 bbls and the 300 BO would fit in there. I just don't have any data on 7383 and small cases.

    I remember the old timers o.f the early last Century referring to duplexing as a 25-75 or a 40-60 mix which I think is an disaster with these two powders. I only shoot the smaller cases in 222, 223 and 7 tcu, most of the time I consider a 30-30 a smaller case.
  3. 9.3X62AL
    9.3X62AL
    I have done a bit of work with WC-860 in the 45/70. Here I have used 6.0 grains of IMR 4198 underneath 48.0 grain of WC-860 with the Lee 405 grain bullet seated to give slight compression. Result has been black powder-like "1873 spec" velocity (1300-1325 FPS) and clean combustion--which was the prime objective. Accuracy is STELLAR.

    In 6.5 x 55 Swede, a full case of WC-860 underneath a 140 grain jacketed bullet (55.0 grains) gives 1896-spec velocities--2475 FPS in my Ruger 77R's 22" barrel. Accuracy has been first rate.

    In 30-06, a full case (60.0 grains) under the Lee 200 grain cast bullet has given 1950-2000 FPS and good accuracy for me.

    Note that these last two exemplars contain ONLY WC-860 powder--NO KICKER. Both produce clean combustion and a very satisfying "BOOM" ​report.
  4. PewProfessional89
    PewProfessional89
    I've been using WC 860 to work up loads in 7.62x54R. I've made it to 52gr. and am still getting a little unburnt powder in the barrel of the mosin nagant with 165 gr. cast boolits. Still have plenty of case capacity left though.
  5. 9.3X62AL
    9.3X62AL
    Heavy-for-caliber bullets--Fed 215 (LRM) primers--and 100% loading density have been the keys for me with WC-860, kicker or not.
  6. PewProfessional89
    PewProfessional89
    Sounds good. I'll load some up with 230gr. Boolits when I get home. Thanks!
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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check