DUPLEX BP Loads

[Grapeshot]

I've read a lot about using a small charge of "smokeless"(shudder) under the main Black Powder charge to make the BP ignite faster and burn cleaner.

I do not argue of the validity of this practice, however, in my youth, my mentor used to speak of using 10 to 20 grains of FFFFg under a charge of FFg to do the same thing and not have the pressure issues that smokless can generate.

Any thoughts on this practice?:Fire:

[missionary5155]

Good evening
I would start out at 5 and work up just to be safe. 1 grain increments.
A feller told me the problem with 4f is it can fall into the primer hole and clog it causing a hangfire. So I stayed away from it.
The fellers shooting when I started up said to use Unique 5 grains for 50 grains 2f and 6-60 and so forth.. so that is how I approached it.
Last time firing my 45-70´s I tried 3F and it does burn cleaner... sure does pack in the case well.
Mike God Bless you.

[badgeredd]

I've read a lot about using a small charge of "smokeless"(shudder) under the main Black Powder charge to make the BP ignite faster and burn cleaner.

I do not argue of the validity of this practice, however, in my youth, my mentor used to speak of using 10 to 20 grains of FFFFg under a charge of FFg to do the same thing and not have the pressure issues that smokless can generate.

Any thoughts on this practice?:Fire:

I'm not sure that the smokeless actually makes the black powder ignite faster, but I am positive it burns cleaner.

Black Prince took the time to tell me about doing this and how it made clean-up a snap. I agree with him on this for sure. Also he said to use no more than 10% smokeless like missionary5155 said.

FWIW, I asked the same question about duplexing 2 types of BP. No one mentioned why it might be a bad idea, so I am glad to see missionary5155's comment, which does make sense to me.

Edd

[hyoder]

I have use dulpex of 2X/4759 loads for hunting. Will almost eleminate fouling, will at least give you time to clean the bore at a convenient time and place.
Do remember to decrease the black powder by the same percentage as the smokeless you add.

[boommer]

I've played with smokeless and 4 f duplex loads. Both will give you cleaner burns,no velocity gain with 4f just cleaner and deviation is a little better I'M just starting to load 4f duplex loads
and shot like 400 -450 between 38-55,45-70,45-90, but this is what I've found with using 10% rule like smokeless. I'm going to work these old school loads and see, but have not seen any hang fires. I like 2400 for smokeless duplex beat out 4759 and unique.

[northmn]

I have played with duplex loads of smokeless and BP. The best powders according to my sources are 4759 and 4227 and should be no more than 10%. If you use 70 grains of BP then 6 grains of smokeless is about right. You would then load 64 grains of BP and 6 grains of smokeless. Paul Matthews claimed that you can figure smokeless in a duplex load at about 1 grain of smokeless equal to 3 grains of BP. My chronograping indicates he is likely correct as it does increase velocity. It also burns much cleaner. So far duplexing has more commonly been done with GOEX and others like it. I would think it a waste with Swiss Powder. A 45-70 will perform more like a 45-90 with it, and still give you the smoke. I do not know its shot to shot deviation for targets, but if one is so inclined it does work OK for hunting. Mostly I shoot straght BP, mostly because it more duplicates the way the guns were used. As to adding 4f I do not remember if it was worth the trouble. Some just mix it in with the 2f instead of putting the 4f over the primer.

Northmn

[boommer]

These are duplex loads in a 45-70 34" barrel with Winchester cases, lee 500gr bullet (493grs)
Fed 215 mag primer. All loads lite compression I've found Swiss don't like much compression
Straight Swiss 1.5 1183 fps avg. deviation of 18 fps
duplex 6grs. 2400 Swiss 1.5 1288 fps avg. Dev 26
duplex 4f 10grs Swiss 1.5 1194 FPS avg. Dev 15
I did this test, all loads the same day at 35 degrees 10 shot stings, just a dry patch during the string, cleaned the barrel when I changed loads.
Is it worth it? I don't know. But I have loads figured out for all my BPC rifles so I need something to play around with. since I got layed off for the winter don,t need go picking up a roller this guy has for very nice price.

[Ernest]

There is a lot of pressure testing in the book shooting the British Double rifle. That book indicates that duplex loads can raise pressures very fast. Be careful out there.