duplexing

[jballs918]

ok guys since 860 is on sale right not at a unheard of price. i have read that on way to get the stuff to work with smaller loads is to duplex it. i really dont understand that whole process and also would anyone have a good mix for that

[ron brooks]

I've never duplexed a load myself but the way you do it is to first put a smalll charge of fast powder, say 4 or 5 grains of Red Dot in the case then the charge of the slower powder on top of it. Alt least this is the way I understand it. I'm sure that someone who knows more about it will do a much better job of describing it.

Ron

[9.3X62AL]

I duplex loads using IMR-4198 and WC-860 in the 45-70 (Ruger #1) as follows--

Dispense 6.0 grains of IMR-4198 into the case.

Dispense 46.0 grains of WC-860 into the case.

Seat 405 grain Lee plain base atop powder to slightly compress the two-phase powder column you've created. A light crimp is nice, too.

My results are 1300 FPS with the above recipe, about like black powder/1873 ballistics. I DO NOT mix the powders--they are poured in stages as above, and the slight compression seems to hold things in place internally.

If there are adjustments to be made to the powder column height to accomodate different boolits, I make "trial" loads using the same measuring device (Lee "spoons", in this instance) with WC-860 (instead of IMR-4198), determine how much of the main charge is required for proper powder column height atop the "fake" starter charge, and go from there. This prevents the mixing of powders entirely.

[Lee]

Sounds OK. Depending on boolit construction, if it is not possible to lightly compress the powder with the boolit;
1. can a"dacron" plug be used atop the main charge to keep things in place???
How well might that work??
2. What would happen if one were to try "Magnum" primers either with or without a duplex charge, or with or without a "plug", or with or without a slightly compressed charge of only 860??

I hope this doesn't present too many variables at once. I'd hate to muddy this threads waters.......................Lee:)

[ron brooks]

Look at this thread I think it will answer most of your questions.

http://castboolits.gunloads.com/showthread.php?t=8642&highlight=860

Ron

[Buckshot]

..............You can check here: http://www.castpics.net/RandD/load_data/45_70/45_70.htm

Castpics surplus powder load data. This info was mostly generated long about 1998 - 1999 or so. I used WC872 vice WC860, but they are similar enough to just substitute WC860 in the straight walled cases.

Smokless powder needs pressure to work efficiently, as we all know. To build pressure there are a few things you can do. One is to use a mag primer. Another is to utilize a heavy boolit and engrave it in the leade. Finally utilize a crimp. Even with all three, in some instances it will not provide the pressure required with the very slow WC860/872 ball powders.

Obviously you could also neck the case down to create pressure but we're trying to make the stuff work with the cartridge at hand. The only other way to accomplish the pressure building is to introduce another means. We can add a small charge of easy to ignite powder at the base of the slower powder so as to create an enhanced primer.

The idea is to merely create sufficient pressure at the beginning so as to provide the slower powder something it may build on, as it becomes involved. I have never used anything slower then 4198 as I was afraid of a 'Pressure Bubble" occuring between the casehead and that column of slow powder atop it. And in fact I did see some indications when trying the duplex process in a 45-90. I would NOT use a very energetic pistol or shotgun powder as the 'Enhancer'.

H4198 seemed to be an ideal powder for the purpose. I know that Ammohead has also used IMR3031 to duplex WC860, to good effect in a 338-06 I believe. My data shown in the load data on Castpics used the Lee 450gr slug vs the 405gr boolit so those velocities appear a tad higher Heavier booit = higher pressure). Also may be due to using WC872 vs WC860.

I started at 1.0gr and found 3.0grs to clean everything up very nicely and that is all you should be looking for. I mentioned Ammohead's use in a BN case, and I know of one other. A freind who at first thought I was an idiot for even doing it surprised me one day for trying it in a 35 Whelen sporter built on a K.Kale Turk M38 action. A full caseload of WC860 and the Lyman 358009 slug had given him very good accuracy at 100 yards, but it did leave some trash behind.

IIRC his velocities were running close to 1700 fps with the straight load of WC860. I believe he used 3.0grs of 4198 as an igniter and his velocity increased into the low 1900's. To date I've not tried a duplex load in a BN cartridge case so I have no personal examples. I can say that none of my duplexing in straight walled cartridges ever showed any signs of pressure except the mentioned 45-90 example and that was flattened primers. I think that was because the long column of WC872 (87.0grs) was acting like a plug more then anything else. The duplexing charge having ignited , and also the base of the charge just began producing pressure faster then the powder column could begin moving.

................Buckshot

[9.3X62AL]

Addendum to above data--I have used only Federal #215 (Large Rifle Magnum) primers in my duplexed 45-70/WC-860 loads.

[jballs918]

ok so as i read this, you take a certain fastburn to get it going. now would anyone have any idea or loading info for this. it seems really scary working on a load that you dont know what to do with