Duplexing slow powders

[ammohead]

rbuck351,

This thread if you go back and read the OPs first request is not about kicker loads. Nor is it about duplexing powder to gain some kind of majical velocity. It is about using powder that burns slightly faster than Kingsford charcoal as a filler instead of an inert substance that sometimes brings its own problems. For example my 257 AI performs wonderfully with condom bullets but it's case capacity sometimes is problematic with cast. The sharp shoulder makes inert fillers problematic also. So a filler that burns with the load charge but at a rate that adds little or no pressure to the curve may be a good thing. This conversation is about that. Or at least it started out that way. It is also a subject that I have wondered about for a long time and would like to see some serious discussion about how to go about it. Not spend time reading about how I shouldn't do it with no more to show than there is no published information about it. Or do this instead. If there were published information about it we wouldn't need to discuss it now would we. If you don't mind I would like to get on with discussing the subject matter at hand.

[ammohead]

five,

Would the burning of the slower powder be that bad of a result? It is not like duplexing with 3031 and 4350 for example where the pressures could get wonky fast. I have seen discussions like that and must admit they kind of give me the willys too.
As I posted previously if the concern was that the filler powder would add too much pressure to an existing load you could maybe back off on that load and slowly increase much as we do when we work up an initial load. I like the idea of COW that disappears before it leaves the barrel. I really like the idea for straight walled cases that are subject to chamber ringing from fillers like 38-55. Now how does one go about it systematically for repeatabilities sake.

Ric,

What boolit are you using? I am assuming it is cast. And what would be the lowest charge of the load powder would you use. I would start there with the rest as filler. Or if high pressures were a worry (and this is going to sound like defeating the purpose) you could start with half powder filler and some dacron increasing the powder filler a grain or 2 at a time until the case was full just to be safe. If the velocity doesn't meet expectations then increase the load charge and decrease the filler charge until it does. Am I making any sense?

[runfiverun]

I'm not a COW fan and would rather use a buffer in some of those applications.
remember that a filler just fills an air hole and a buffer is a compressable inert material.
they both have their place.
a Dacron type filler works better in the sharp shouldered cases and is used to raise pressures and replace some of the powder.
it just keeps the powder against the primer and tricks the case into thinking it is smaller than it is.
where you get into trouble is leaving an air gap in the case so the wad of filler can get blown forward and push air against the base of the non moving boolit.
you just compressed air and get the ringed chamber.

the buffer does much the same thing but is used on a larger powder amount.
it protects the base of the boolit and becomes part of the ejecta weight.
if you have a 75-80% case fill but are getting erratic velocity's then switching over to a buffer can be helpful.

you can combine the two in some situations.

if you could get a consistent predictable amount of the filler powder to burn then using it would pose no problem.
35-40 grs is just an awful lot of powder to predictably burn, especially on top of 42grs of powder.
I'm having a hard time mentally predicting a pressure or seeing where the secondary burn would come into play with a 50-50 split of the two types.

now this may seem like an off the wall suggestion.
but a combination of the initial powder a filler of the slowest of the two powders and a buffer in the neck of the case might just turn the trick.
you could control the compression and the volume of the secondary powder.

it might take quite some time to get just the right combination though.

[wmitty]

Would the correct way of approaching this be to load three rounds each in charge increments of 5 grains of the Turk powder while placing enough of the "filler" powder on top to allow the boolit's base to compress the powder column to prevent mixing? I've used 4227/ 860 loads in the .375 with success, but haven't tried what is being described here. Looks like a good idea if the Turk powder is slow enough to not cause excessive pressure with the "reactive filler".

[Nobade]

His original load with the Turk powder is relatively light, so adding that much 860 will likely take him up to a normal full power load. Of course if the first load fired shows excessive pressure or velocity, don't fire any more. Do something different. I say this after quite a few years and many thousands of rounds fired learning about this type of loading. Not once have I seen something like this produce an unexpected reaction in a rifle with an expansion ratio like a 375 H&H. I would, however, not try it in a 7mm stw or anything that could possibly produce close to normal pressure with 860 by itself.

Sent from my Moto G (4) using Tapatalk

[KYCaster]

I think I would approach this from the opposite direction....start with a full case of WC860 and substitute the Turk powder as a kicker in 5 gr. increments till you get the results you're looking for.

Seems like, if your 45 gr. Turk load is anywhere near approaching a full power load then that doesn't leave you much wiggle room for a "filler" that will add its own pressure.

All my experience with WC860 is with cases much smaller than your 375H&H, 7.62X39 the smallest and 35 Whelan the largest. Based on that, I would GUESS that you can get close to 2000 fps with a case full of WC860 and a 300 gr. bullet.

Start with that and add the Turk powder a little at a time should tell you very quickly what you want to know.

Good luck and be careful.
Jerry

[waksupi]

I'm using a 285 gr. bullet from an NOE mold. I believe my course of action, will be to continue adding one grain at a time of the Turk while reducing the "filler" and chronograph the results, while looking for any problems. If the pressure curve and velocity raises as I think it will, I believe this will be a safe practice in this particular chambering. As to others? They would need to be experimented with separately, as a .375 H&H is rather generous in what it can handle. It would probably take something pretty extreme to hurt one.
Now all I need is time to do this! And for it to stop raining!

[runfiverun]

ahh your getting the water too.
it has been stupid wet this year down here.
I got enough ground water to dig a 10' well and export it to the desert.

anyway count the filler as either boolit weight or powder weight.
with an inert filler it acts like powder weight.
with a filler that remains solid I count it as boolit weight.

if you consume some of the extra powder it counts as both so you need to be real careful.
the more of the under powder you add the closer your gonna come to burning more of the filler powder.

[richmanpoorman]

Well, I guess I have been told off ! Now, perhaps you could do 2 things:
1. Point me to a reloading manual published by a respected powder maker that has duplex smokeless loads in it.
2. Explain to me the advantages/gains from these duplex loads vs published data for cast bullet reloading.
thanks RMPM

[ammohead]

Well, I guess I have been told off ! Now, perhaps you could do 2 things:
1. Point me to a reloading manual published by a respected powder maker that has duplex smokeless loads in it.
2. Explain to me the advantages/gains from these duplex loads vs published data for cast bullet reloading.
thanks RMPM

RMPM

If it was already in a reload manual we wouldn't need to discuss it here. Why would a powder manufacturer that sells it's product for upwards of $30 lb want to help me use powder selling for $8 per pound?

Many of us have large amounts of powder we bought at a very inexpensive price that we want to be able to use if that is the only option left to us by our sometimes oppressive govt. There is no published data for WC857 either but I can buy it at close to $10 pound and it equals some factory loads in my 270 win with no sign of excessive pressure. Is THAT not worth your time?

My point is that I have been talking to some of the members of this board and other boards that came before it since 1998 and the purpose of many of those conversations has been to learn something new that the information about is simply NOT published anywhere else. That is the whole purpose of coming here. My good friend the late BruceB helped me and many others on this board achieve awesome performance using cast boolits in our M1A Springfields. All the time being assailed by naysayers such as yourself. Now it is common knowledge that such a thing is not only possible but not scary in the least anymore than using the right powder in a 30-30. Naysayers told Columbus he was nuts.

[ammohead]

five,

The desert has been getting the water too. The Truckee River coming out of Reno has been going over the spillway at Derby Dam for like 3 months now. That is a lot of water. It is great to see all the lakes full again.

[runfiverun]

dang man water in the Desert.

I might have to swing down through Wells and see if the Desert comes out in bloom.
that has to be one of the most beautiful sights in the world when everything in a usually flat barren expanse just pops out flowers like that all at one time.

it's like seeing the high desserts in Wyoming after the first good snow fall of the year,
or when all of the Monarchs are crossing the Desert down on the southern Nevada-California line.

[rbuck351]

Well, if using 42grs of Turk produces 2450 fps, it already is producing enough pressure to burn a slower powder rather well. Fill the rest of the case with 870 or what ever and it could burn the whole charge better than you might think. A case full of 870 is very probably safe. Substitute turk for the 870 a few grains at a time until the pressure gets high enough to suit you. Turk sounds to be a medium burn rate rifle powder. Once again do not start with a bunch of a faster powder and fill the case with a slower powder. It is not safe to start with way to much pressure and back off till it's safe. Yes, you can work up a safe load using turk and 870 but not by starting with a healthy charge of the faster and then filling the case with a reactive filler as you have no way of knowing just how well the filler is going to react. Start with the slower and build up the faster until it's time to quit. This will tell you just how much of the faster can be added to the slower. I am not a naysayer on duplex charges as I have had good luck with them. But to top off a case that already has a fair charge of a faster powder is taking a wild guess as to what will happen.

[waksupi]

Well, if using 42grs of Turk produces 2450 fps, it already is producing enough pressure to burn a slower powder rather well. Fill the rest of the case with 870 or what ever and it could burn the whole charge better than you might think. A case full of 870 is very probably safe. Substitute turk for the 870 a few grains at a time until the pressure gets high enough to suit you. Turk sounds to be a medium burn rate rifle powder. Once again do not start with a bunch of a faster powder and fill the case with a slower powder. It is not safe to start with way to much pressure and back off till it's safe. Yes, you can work up a safe load using turk and 870 but not by starting with a healthy charge of the faster and then filling the case with a reactive filler as you have no way of knowing just how well the filler is going to react. Start with the slower and build up the faster until it's time to quit. This will tell you just how much of the faster can be added to the slower. I am not a naysayer on duplex charges as I have had good luck with them. But to top off a case that already has a fair charge of a faster powder is taking a wild guess as to what will happen.

That is pretty much how I have proceeded. 10 gr. of the Turk filled with WC860 is giving me around 2050 fps. According to theory, I would only need another 8.5 gr. to reach the velocity I need.

[PowPow]

Does slight mixing of the primary powder and "filler" powder within the case have much effect on velocity and consistency? If so, what do you do to improve it?

[waksupi]

Does slight mixing of the primary powder and "filler" powder within the case have much effect on velocity and consistency? If so, what do you do to improve it?

That is not ideal. They should be slightly compacted to remain separate, although I did a little experimenting with that. I wouldn't want to get carried away with that line of experimenting without pressure measuring devices.

[runfiverun]

the only one I know that was mixing [blending] powders was Starmetal.
he never did tell me what 2 powders he was using though.

the divider paper I mentioned before is useful if your putting a fine powder on top.
it is just to stop migration.

[jonp]

Pulled after reading more comments

[KYCaster]

the only one I know that was mixing [blending] powders was Starmetal.
he never did tell me what 2 powders he was using though.

the divider paper I mentioned before is useful if your putting a fine powder on top.
it is just to stop migration.

If Starmetal did it, it must have been "The World's Finest Propellant".

Jerry

[runfiverun]

...
or Herters brand.