Duplex load

[TD1886]

Thanks TD1886, tomorrow I will start!

You're welcome, thumbs up and good luck.

[nueces5]

Well, the first test is with two shots of 3, 3.5 and 4 grains of H2400, the rest of the brass with a very slow gunpowder, which is used for the .50 BMG here in Argentina.
I couldn't use the chronograph to measure speed, but it shows that it is a powerful shot.
All loads within an inch at 50m, with mediocre support. So more than satisfied.
Now I must measure with the chrono and see which is the most convenient load,

[uscra112]

Sure would like to see some pressure/time curves for "successful" loads.

I admit the utility of it given the difficulty in obtaining better powders. But am might glad I'm not short of any that I commonly use nowadays.

[deces]

I have a question, are there any reloading books that cover Duplex loads at depth? I'd really like to read more about this in print.

[nueces5]

I have a question, are there any reloading books that cover Duplex loads at depth? I'd really like to read more about this in print.

I think that every time the manuals show less and less, to avoid having legal problems
There is much more info here on the forum.

[Nobade]

I really doubt that is something you are going to find anything in books since it is so far away from the norm. Your best resource is right here from people who have done it and written about the results. Remember, we aren't trying for super performance. We're just trying to use up super cheap and otherwise unsuitable gunpowder in an application it is not designed to be used in.

[MUSTANG]

Nueces5:

Any further testing and performance reports?

[Maven]

All, I've tried duplexing WC 860 (with WLR magnum primers) with several propellants in my "as issued" Type 56 SKS (spike bayonet). ~3gr. CLAYs + 21gr. 860 was a waste of time as was 4gr. Lil' Gun + 20gr. 860: The first wouldn't eject and left the cases quite sooty whereas the second tossed them pretty vigorously, but left unburned powder in the magazine well. Neither was especially accurate @ 50 yd. from a rest. However, last week I tested Ian's (from The Art & Science site) suggestion to use 4.5gr. Lil' Gun + 19.5gr. WC 860 and was rewarded with great accuracy, mild ejection, and clean cases. Btw, the CB was a ~160gr. C.E. Harris design + gas check, sized to .3155" and seated @ 2.125". No crimp was applied. That particular powder combination and bullet seating depth allowed for enough compression to keep the starter charge in place.