Mixing powders

[chas442]

It appears to be common knowledge that a case with 100% fill will be somewhat more consistent than a case that is less than filled to capacity. Has anyone tried to, say, put 25 grains of 4895 and filled the case to capacity with 870 on a 30-06 case?
The 870 regardless of manufacturer is much slower than 4895. It may present more flash but at the same time it will give a more consistent burn with a full case.
Powder types are just arbitrary at this point.
Has anyone tried it?

 

[chas442]

One more thing, Putting 4895 on the bottom of the case and then putting the 870 on top to thje point that the 870 is compressed.

 

[Jim Watson]

It's been done, but it is not commonly found on the internet or in manuals. OLD gunzines maybe. Or just buy some 4350.

 

[macgrumpy]

So where did you hear about doing this?
Jim Watson, If it's been done and you knowledgeable about it, could you provide a reference?

Everything I've ever read about smokeless powders has said that it's not safe to mix different types of powder and considering that you can't predict how the powder mix would burn I'd say that it's a bad idea. Maybe some rocket scientist would be qualified to mix powders but I doubt that most of us would be safe trying it on our own.

 

[ArchAngelCD]

I would not do it because it's not safe. No matter what we "think" we can't know what pressures are being generated without pressure testing equipment.

Like said above, use 4350 and your 30-06 case will be full. I use nothing but 4350 in my 30-96 but for M1 ammo.

 

[Decoy80]

I have read of handloaders duplexing,which you are talking about. Some even triplex powders in a load. I am no expert at handloading by any means. During component shortages I know a fellow who got some surplus WC 860 and duplexed the load on 30-06 and larger magnum rounds with moderate success due to necessity. I love me and once I max out a published load I sneak up a tenth of a grain until I have harvested all my gun and myself are capable of. Call me a big chicken Im guilty.

 

[Grumulkin]

I've tried duplex loads once and very cautiously. In my very limited testing with one cartridge there was no advantage. The scenario was the 460 S&W Magnum I had loaded with rifle powder. Accuracy was pretty good but pressure low with a full case and I wanted a little more oomph. As I recall, as I added a slow pistol powder (still pretty fast by rifle standards), accuracy was adversely affected and the effort was abandoned.

I think it's possible for some quite experienced handloaders to assemble duplex loads safely. While it's true you can't measure pressure without testing equipment, handloaders estimate pressure all the time; it's no different with a duplex load.

 

[kingmt]

This isn't meant to be taken as a "How To" but rather meant to deter instead of encourage.

With a few exceptions powder doesn't burn very well unless it has a great deal of heat & pressure. The more it has the better it burns. 870 has to be very high to get going but once it does it also creates massive pressure. I've felt the break over point & is impressive to say the least.

It isn't unheard of to prime a slow powder with a fast one on bottom. Say Xgn Bullseye to prime XXXgn of 870.

What would seem more difficult to me is to blend two powders to get the burn rate your looking for. It's done by manufacturers but I personally haven't did it myself. This isn't related to mixing two of the same powders with different lot numbers which I'd consider safe.

 

[thomas15]

I would personally never do this even on a dare. However, for personal enrichment, I take classes at my local community college. This semester I'm taking Organic Chemistry 2. While I'm not a chemist or even a scientist, I know a few things about organic reactions. In my opinion it would be possible to predict how a mixture of powders would react if you have the physical property data before hand.

I've completed lab exercises where we mix two compounds with known melt points and came up with a third melt point lower than either of the two. This is one way to determine the identity of an unknown mixture(s). But again I wouldn't do the op proposal because there are many other considerations besides combustion rates and pressure curves to consider and for most, if not all of us, this is a hobby. There really isn't any compelling reason for the private handloader/firearms enthusiast to experiment in that area. We have literally dozens of acceptable powders to choose from that are formulated and tested by knowledgeable chemists. If you want to use a specific powder and also have a full case, fill the void with some kind of inert substance and call it a day.

 

[kingmt]

If you want to use a specific powder and also have a full case, fill the void with some kind of inert substance and call it a day.

I wouldn't even advise to try this. If your so daring then you should start with a load reduced to nothing near enough powder & work up. At one time I'd hold powder against the case head with a little plug of tissue & it increases pressure quite a bit.

 

[Bart B.]

Mixing powders renders the "SAAMI Twist" method of cartridge handling questionable for ballistic measurements. It's not an exact science and smart reloaders don't do that.

 

[thomas15]

I wouldn't even advise to try this. If your so daring then you should start with a load reduced to nothing near enough powder & work up. At one time I'd hold powder against the case head with a little plug of tissue & it increases pressure quite a bit.

I probably should have been more specific. My Dad loaded up 30-06 using cast bullets and gas checks for a 1903 Springfield. They were reduced loads obviously so he added corn meal which was a common practice back then. Because I was a kid I didn't pay attention to the specifics but I'm sure it's in print out there. By "inert" I wasn't thinking about a noble gas, just something that takes up space and doesn't participate in the combustion reaction.

ON EDIT: PV=nRT Change one of the values and the others are affected.

 

[JimKirk]

I would not call it mixing but duplexing... triplexing ... been done by several ... yes it can work ,,, is it worth it ...NO ... not when we have plenty of useful powders that work with out all the trouble .... But if I were in a SHTF type situation and that powders is all that I could get ... Yeap ...I'd go for it ...

 

[ArchAngelCD]

Guys, I don't think the OP was taking about duplex loads. He specifically said he was going to use 4895 and then use 870 as a filler for the rest of the case. That is not a duplex load at all and not a good idea.

If the OP wants to use a filler use Cream of Wheat BUT, it is not necessary in bottleneck rifle cartridges like the 30-06. Like I said above, use 4350 instead of 4895 and you will fill the case.

Try a 165gr SGK or 168gr SMK over 57.0gr IMR4350 and you have a full case and an accurate load. The load works equally well with H4350 and the large rifle primer of your choice.

 

[Jim Watson]

macgrumpy, my first exposure to duplex loading was Elmer Keith's general description, without recipes. He said that the OKH work on duplexing was actually installing a flash tube to ignite powder from the front of the charge. The term was used to confuse Nazi spies, this being done during WWII. He said that when they got around to loading two powders, that was "double duplexing."
Dick Casull started out with duplex and triplex loads in overloaded .45 Colt leading up to .454. Availability of Win 296 made that unnecessary.
Harry Pope and others used and still use duplex loads with an ignition charge of smokeless under black. It makes it unnecessary to wipe the barrel during a match.
A friend and I extended that to his .450 Black Powder Express and used one of the fake powders as a "filler" over 4198. Velocity was considerably increased, regulation went to pot, and we didn't do that any more.

I would say that using H870 as a "filler" over a half load of 4895 would precisely be duplexing. The 870 is not inert like CoW. Which is not a good idea in a bottleneck case anyhow.

The SAAMI Twist seems not to do much to a compressed load.
PV=nRT seems to have little to do with an open system, irreversible change due to chemical reaction, although I see it cited pretty regularly.

 

[Walkalong]

....................... It's not an exact science and smart reloaders don't do that.

I have to agree. There is no need to get 100% load density for 99% of reloading.

There are some great rifle loads that are not 100% load density. And besides, if it lowers the ES a couple of digits, that doesn't mean A: It is even more accurate. B: You can shoot the difference.

Too many more important things to worry about.

 

[HankB]

When Casull was first developing his .454, he used duplex and triplex loads - but he didn't mix the powders, he loaded them so they'd lay in distinct layers and seated the bullet so as to compress the powder charge, and keep the layers separate. The advent of new powders made this technique unnecessary to achieve the velocities he wanted. I've heard of using a small charge of smokeless right above the primer to facilitate cleaner ignition with a large black powder cartridge, but not being a BP shooting myself, can't say if it's safe or effective.

I wouldn't seriously consider blending different powders, even if they're similar - for example, even mixing IMR4831 and H4831 would be a "no go" for me. You really DON'T know what you're going to get, and some unexpected non-linear effect could cause a real problem. Ditto with layering different smokeless powders in a modern case, either rifle OR pistol.

The only "safe" mixing or blending technique I know of is to blend two different lots of the exact, same canister powder together. Say a person purchased two cans of IMR-4350 to load up a bunch of ammo, and then found out his batch would require 1 1/2 cans - but what he bought is 2 different lots. I don't see a problem with blending them together and working up a new load, especially since canister powders are controlled pretty closely as to burning rate already.

As Jim Watson mentioned, another "duplex" technique didn't initially use different powders, but rather a tube inside the case to direct the primer ignition to the front of the powder charge. Old Elmer Keith - when he was working for the military - was inspired by its use in artillery and tried this in .50 BMG, getting a couple of hundred feet per second more velocity with normal pressures. IIRC, cost and problems if the gun had a slightly oversize chamber prevented further development for small arms.

 

[stringnut]

There was quite a bit of information published about duplexing. Some of it mentions some pretty interesting results such as blown primers, bolts that had to be opened with a hammer, and once in a while a gun coming apart. None of that for me thank you very much. When all this was going on there was no pressure testing equipment and darned few chronographs. All load work up was done using pressure signs which are notably unreliable. This lead to some outlandish claims for velocity. The Gibbs line of wildcats used duplex loadings in some cases and sometimes long flash tubes. When loaded to safe pressures duplex loading and other chicanery was found to have no advantage when tested.

 

[kingmt]

I probably should have been more specific. My Dad loaded up 30-06 using cast bullets and gas checks for a 1903 Springfield. They were reduced loads obviously so he added corn meal which was a common practice back then. Because I was a kid I didn't pay attention to the specifics but I'm sure it's in print out there. By "inert" I wasn't thinking about a noble gas, just something that takes up space and doesn't participate in the combustion reaction.

ON EDIT: PV=nRT Change one of the values and the others are affected.

Are you sure he was putting corn mill in a load case? I use it over a fast powder with a piece of tissue paper to hold it in the bottom of a case I need to push the shoulder forward or neck out & shape it to my chamber. The is no bullet on top. The powder can't get out of the neck fast enough so it shoves the brass out of its way ironing it to the chambers walls.

 

[reddog81]

If you want to use a filler, use a filler - not gunpowder. There are tons of different powders out there and if you think filling a case to 100% capacity is necessary I'd just find the correct powder.

 

[Varminterror]

I would personally never do this even on a dare. However, for personal enrichment, I take classes at my local community college. This semester I'm taking Organic Chemistry 2. While I'm not a chemist or even a scientist, I know a few things about organic reactions. In my opinion it would be possible to predict how a mixture of powders would react if you have the physical property data before hand.

I've completed lab exercises where we mix two compounds with known melt points and came up with a third melt point lower than either of the two. This is one way to determine the identity of an unknown mixture(s). But again I wouldn't do the op proposal because there are many other considerations besides combustion rates and pressure curves to consider

As a guy with degrees in chemistry and chemical engineering (and physics & microbiology), and having worked in munitions development projects, yours is a really poor analogy. Exact example of knowing enough to be dangerous. The deflagration curves of self-oxidizing smokeless powders, pressure and temperature dependent as they are, are a LOT more complex than determination of a blended melting point. The chemistry behind duplex powder burn rates IS known, but the experimental design for these products is NOT a double-pressure-proofed civilian firearm, it's a much more robust firing fixture.

Duplex loads can be developed, I've worked with some myself, both professionally and privately, but the advantage over other commercially produced powders just isn't there.

One thing I do want to be very clear about - the powder column does NOT burn back to front like a fuse being pushed down the barrel. In general, for a well suited load and powder, the entirety of the charge is gasified/pyrolyzed within the first few inches of the barrel, as such your duplex load is not acting like a "rolling start," or "shifting gears," but rather acting as one blended gaseous mixture.

Just buy a better suited powder.

 

[thomas15]

As a guy with degrees in chemistry and chemical engineering (and physics & microbiology), and having worked in munitions development projects, yours is a really poor analogy

I'm very impressed.

Duplex loads can be developed, I've worked with some myself, both professionally and privately, but the advantage over other commercially produced powders just isn't there.

I know it's possible but your the chemist, the rest of us are not. My understanding is that the big makers of ammo blend their powders to get what they want but again layman such as myself don't have the understanding or equipment to do this correctly.

 

[Varminterror]

I'm very impressed.

I know it's possible but your the chemist, the rest of us are not. My understanding is that the big makers of ammo blend their powders to get what they want but again layman such as myself don't have the understanding or equipment to do this correctly.

While I can always appreciate sarcasm, I don't see the point in being argumentative when your post agrees with mine.

It's not something the average reloader, or even advanced reloader should ever bother with. Your post I quoted over-simplified the complexity of this undertaking with an unrelated experiment of simple PHYSICAL material properties to analogize against a highly complex experiment of CHEMICAL material properties. It's apples and oranges.

 

[Skeet 25]

Very good reading for a newbie like me, not that I would ever think of doing duplex loads . The terminology was very advantageous.

 

[Bart B.]

My understanding is that the big makers of ammo blend their powders to get what they want

Yes, but only different production runs of the same powder to get consistent uniform retail lots to sell to reloaders.