Mixing Different Powders Together

[turbo54]

I'm interested in having an intelligent discussion about mixing/blending powders.

If all you have to say about it is "Don't", please save it.

If you can qualify the "Don't do it" with rationale and reasoning, I'm all ears.

I know for a fact it is common practice for big cartridges, such as 460 Weatherby and 500 A-squared, to drop 5-10gr of a fast pistol powder in the case on top of the primer, followed by a heavy charge of slow rifle powder. Usually this is only for compressed charges, to keep the pistol powder by the primer, and not get mixed throughout. They call this a duplex load.

I'm more interested in the idea of blending two fairly alike powders together, so wind up with something in between.

Say you're loading for a cartridge that works well with Varget and H4350, but Varget is a bit too fast and H4350 is too slow. What would happen if you mixed the two 50/50? Speaking theoretically, so as to assume you had a homogeneous (NOT STRATIFIED) charge, would you in fact end up with a burn speed between the two?

Seems to me you would, though I'd expect it to be closer to the faster powder if mixed 50/50, because the slower powder would burn faster than normal on account of the faster powder present, and the higher pressure...?

Either way, I don't see how a 50/50 mix of Varget and H4350 would burn faster than just Varget alone. Thoughts?

It seems it would be safe to start at a charge weight known to be safe with the faster powder.

Bottom line: if Varget is safe to use, and H4350 is safe, how could the two mixed not be safe?

I know I've read posts from chemical engineers here on the hide commenting on burn chemistry...hopefully one will chime in and educate me.

Thanks!

 

[Sniper260]

Interesting because I have seen it done with some factory ammo.. I forget what it was that I opened up but there was two different granules in there.

 

[ChrisGarrett]

Well, two close powders and you're probably in the ballpark, if you start low and work up.

You start mixing N110 with MagPro and all bets are off.

Elmer Keith used to make tri-plex and du-plex loads using 3 and 2 different powders, but I think that he was stacking them and not blending them.

I've always said here and elsewhere, that if you had enough time to experiment and weapons to eventually blow up, you could get BlueDot to work in say...a 300WM cart.

Remember, it's always the pioneers who take the first arrows.

Go get 'em Sparky.

Chris

 

[buffybuster]

One time I got nearly a full jug of Varget/H4350 (previous person had unintentionally emptied some hoppers of Varget into H4350 jug. Near as I could tell it was about 40% Varget to 60% H4350 (though can't be sure). I was going to toss it in on the lawn but decided to shoot some light loads for positional and caseforming. It actually worked well so I decided to develop a .308Win load. Ended up getting a fantastic load from that powder blend. About 100% load density, 2650fps with 178HPBT's and single digit ES. It was an awesome load and I wish I could duplicate it....... but I don't know what the exact % of Varget to H4350 was.........

I made sure the powder was well blended and never had any weird things happen. Burnrate seemed to be something between Varget and H4350, as you would expect. I am NOT RECOMMENDING the practice.

My WAG is if the powders are very similar in composition and burnrate, then it's probably OK. Red apples and Green apples together still make apple pie..... But two dissimilar powders might not be so compatible.

 

[turbo54]

Funny you mention fast pistol and slow rifle...

An old timer at my gunclub was telling me he got a 55 gallon drum of milsurp HS6 (or equivalent) and another of the super slow 50 Cal powder....and he mixed them for years. His claim was that he had to shake the cartridges after driving out to the range to remix them, or else his standard deviation went to hell. No idea if he was spinning a yarn...seems likely.

 

[buffybuster]

Another WAG: If you have two powders of vastly different burnrate; if they're stacked (not mixed) then the faster powder would act like an accelerant to the slow powder. If they are mixed, that might end up with a double pressure spike, which might be a bad day.

 

[P7id10t]

Thanks for posting this question, thinking along the same lines myself today.
Loading 47 grains RL17 for 308 and it's just at the limit of the case capacity with proper bullet depth (measurement with depth gauge.)
17's too damn slow but think mixing it with 4064 or VV550 might be beneficial.
Would try stratification first. Then homogeneous mixing (in theory).

I've done this with the driveway with my kids, trying to foster a new generation of pyromaniacs: lay down a patch of powder, a mixed patch and then horizontally stratified patches.
single and horiz. stratified patches burned predictably, mixed one burned at what I would expect the faster powder would do with a late "grand finale", I expect from the slower powder.
Used to work a lot with natural gas, propane and butane and playing with flame speed.

Anyone else seen this or something similar (net effect of mixing powders) ?

Used to do this as a kid with saltpeter and sugar and it amazed me how it would burn through asphalt (2"+) or destroy small pockets of concrete.

 

[oldfatguy]

Biggest problem would be maintaining a homogenous mixture or consistent stratified load.

OFG

 

[insight3b]

I do it with the partial bottles I have left over. I'll mix the remnants of 1lb RL15 with the remnants of 1lb VVN540 and usually end up with enough powder to load 50 rounds with a light/start charge. I use this ammo to break-in barrels or take it to local field shoots with my buddies.

 

[sinister]

Of course it's been done before.

Kids, don't try this at home.

 

[turbo54]

Sinister, I'm not sure I understand what General Dynamics was trying to achieve there... Do you have any more information? It appears they weren't blending for the purpose of achieving a different burn speed. Looks like they were trying to get more propellant into the case.

H4831 is bulky and you're commonly case-capacity limited with it.... So load a compressed charge of H4831, and "fill in the cracks" with some Winchester 780???

 

[jasent]

Only issue I think you would run in to with said powders mixed is inconsistency. How would you know your mix is perfectly blended.and if the granuels(I'm not familiar with h4350) were not the same size the smaller kernels could sift down and slowly "unblend"

 

[turbo54]

Secondary question:

I've run most of the Hodgdon extreme powders. I have a hunch the only difference between different extreme powders in Hodgdons lineup is the size/shape of the kernels.

Can anyone confirm/deny this?

 

[CanSniper]

Only issue I think you would run in to with said powders mixed is inconsistency. How would you know your mix is perfectly blended.and if the granuels(I'm not familiar with h4350) were not the same size the smaller kernels could sift down and slowly "unblend"

This was my thought as well. Might have better luck just dumping 2 charges. Maybe Varget on bottom and 4350 on top, weighing each charge seperatly. I would think it would be like the crumbs in the bottom of your Cookie Crisp cereal (LoL) always setteling to the bottom.

 

[turbo54]

Still speaking theoretically here...

Even though Varget and H4350 are very similar in size/shape, the concept of them separating is troublesome.

BECAUSE they're so similar, it would really be a hassle to test how well blended the mixture was.

Perhaps a good way to test the blend would be to try a mixture of two powders slightly more different. Such as Varget and Retumbo, as you can readily distinguish between these two. Weigh out a few ounces of each, and mix them together. Play with the bottle to attemp to "induce" separation. Take it with you in the car for a few days or something. Dump the mixture in the chargemaster and throw a few charges. Pick through the thrown charges, separating the Varget and Retumbo out from each other, and then weigh each sample. Tedious, but that would tell you if they're prone to separation. This all makes the assumption, however, that Retumbo is at least as likely as H4350 to separate out of a mixture with Varget. Personally, I think this is a fair assumption to make. The size/shape of Varget vs. H4350 is damn close to the same, and I think that decreases the risk of separation.

To begin load workup, I would think the safest approach would be, if you were targeting say 40gr, to weight out 20gr of each powder, mix them, and then charge a case with the mixture - NOT just mix up a pound of Var350 and let it rip.

Thanks for the responses so far. This has been on my mind for a couple years now. Always wanted to start a thread about it but didn't because I thought people would flame the shit out of me for even thinking about it.

 

[ChrisGarrett]

Secondary question:

I've run most of the Hodgdon extreme powders. I have a hunch the only difference between different extreme powders in Hodgdons lineup is the size/shape of the kernels.

Can anyone confirm/deny this?

Well, IIRC, the Extreme lineup is less temperature sensitive.

You still have relative burn rate differences between various powders within the Extreme lineup.

Chris

 

[Sniper260]

I'm still interested in some recipes. I believe 100% that a mixture of two or three powders could potentially have better success rates than the normal reloading powders by themselves. I think it all comes down to burn rate and pressure consistency. I have deviated many times from load data trying different powders in rounds that have no published data. Started low and worked up, thats how I found a load I still use today.

 

[turbo54]

Well, IIRC, the Extreme lineup is less temperature sensitive.

You still have relative burn rate differences between various powders within the Extreme lineup.

Chris

Correct. My suggestion was that different burn speed characteristics are a result of the different size of the kernels, not the chemical makeup, which explains why the Hodgdon extreme lineup of powder gets larger and larger all the way up the line. This decreases the surface area/volume ratio, slowing the burn.

The shape of the combustible makes a huge difference in how fast it burns:

Take 2 sheets of paper, and cut one of them up into tiny squares. Fold the other into a densely packed cube. Spread the tiny squares out into a thin pile. Light both the "cubed" sheet and the cut-up sheet on fire and observe which one is done burning first.

 

[ChrisGarrett]

Correct. My suggestion was that different burn speed characteristics are a result of the different size of the kernels, not the chemical makeup, which explains why the Hodgdon extreme lineup of powder gets larger and larger all the way up the line. This decreases the surface area/volume ratio, slowing the burn.

The shape of the combustible makes a huge difference in how fast it burns:

Take 2 sheets of paper, and cut one of them up into tiny squares. Fold the other into a densely packed cube. Spread the tiny squares out into a thin pile. Light both the "cubed" sheet and the cut-up sheet on fire and observe which one is done burning first.

Actually, Hodgdon states that there is NO difference in burn rates between powders such as H-4831 and H-4831sc (short cut) so I don't think that that's the issue.

The are ballistic equivalents, but one is shorter and therefore measures more easily.

Chris

 

[turbo54]

Actually, Hodgdon states that there is NO difference in burn rates between powders such as H-4831 and H-4831sc (short cut) so I don't think that that's the issue.

The are ballistic equivalents, but one is shorter and therefore measures more easily.

Chris

It has been my personal experience with H4831 and H4831sc there is some difference between the two.

If you measure the average length and diameter of these two powders though, then calculate the surface area and volume of them, you'll find their SA/V ratios are very similar.

H4831sc is not only shorter, it is fatter than H4831.

 

[EddieNFL]

...different burn speed characteristics are a result of the different size of the kernels

Along with chemical composition, retardant coating, shape, porosity, density and, in some instances, perforations.

Duplex/triplex loads is an interesting subject, but with the plethora of powders available, I don't see a need. If you have the tech data and necessary equipment, go for it.

 

[ChrisGarrett]

It has been my personal experience with H4831 and H4831sc there is some difference between the two.

If you measure the average length and diameter of these two powders though, then calculate the surface area and volume of them, you'll find their SA/V ratios are very similar.

H4831sc is not only shorter, it is fatter than H4831.

That's not what Hodgdon says on their website and in their pamphlets. They are the same ballistically.

Maybe you're seeing velocity changes due to X, Y or Z variable, in your components?

Often times we get 'lot to lot' variances and perhaps this would be why you're seeing a difference?

Powder is energy and energy is due mostly to percentages of nitrocellulose and nitroglycerine. There are tons of additives that matter to lessor degress, like flash retardants, graphite for slickness, progressive burn rate additives, et al.

I'm not going to belabor the point. I'm just saying size probably plays less of a role in the equation--chemical content of NC/NG being the primary reason why one powder per unit weight, has more energy than another.

Chris

 

[turbo54]

Along with chemical composition, retardant coating, shape, porosity, density and, in some instances, perforations.

Yes of course. I wasn't trying to imply the only difference between any/all powder was shape of the kernel.

However, it seems to me that because Hodgdon only has a few "extreme" powders, they all have the same greenish color, and each step slower powder is larger, it may be because the only difference amongst them is their size. It was just a thought, I have no idea if it's true. I guess some samples in an MSGC would tell most of the tale.

Duplex/triplex loads is an interesting subject, but with the plethora of powders available, I don't see a need. If you have the tech data and necessary equipment, go for it.

Yes, it is an interesting topic and I'm glad we've gotten this far into it without schmucks telling us we're retards for even talking about it.

I disagree a little with you on "need" though. We are indeed very lucky to have the propellant choices we do, and there is hardly a cartridge in existence that doesn't have at least a "pretty" good choice powder avaialble.

However, there are ~200 powders available for purchase in existence, to cover tens of thousands of cartridges. Further, many of those ~200 powders are direct competitors to one another and overlap either a lot, or completely, thus taking away from the full array of speed/energy choices. Even more limiting is that Hodgdon has offered us these extreme powders that hardly react to varying temperature, and are extremely consistent - and they only offer these powders in rather large "steps" in burn speed (though H1000 and Retumbo are awful close).

It is well known the "big guys" have powders custom-blended for specific cartridges (by blended, I mean during manufacture of the powder itself, so that all kernels are the same) and loadings to optimize them.

Back to need: I've found even in my limited cartridge loading experience, there is often never just the "right" powder. 7mm-08 and 284 are good examples of this. For 7mm-08, Varget and H4350 work quite well, but Varget is too fast and gives ~90% load density. H4350 works better, but you're case capacity limited. What is "needed" is something right in between. 284 needs a powder in between H4350 and H4831.

Can we get very good performance without blending? Yes!

Can we improve performance? Seems likely.

Is it worth the trouble? Maybe not. Not unless a reliable and reasonably easy way is found to do it. If I can mix up some Varget/H4350 @ a 50/50 ratio and gain 35fps at the same pressure, I'd probably do it.

A lot of people point bullets, and that seems like a bigger hassle. Is it "needed"? No, but it certainly provides a performance gain.

 

[Guest]

If you really want to know your going to have to dig for it.
That said I have built duplex and triplex loads for the old 375H&H, 30-06 as well as the .308 win. With a proper triplex load you can jump speed 125-175FPS in any one of those rds.
Max pressure is the same, but you extend the time line. Think about how you would do that!
The reason you see a faster powder over a primer in large loadings is, to insure the main charge will lite in all weather, and to stop hang fires.
I will not tell you the charge weights or powder use as I do not want to be responsible for anything that goes wrong, but I will tell you the last powder charge installed in the case, has a much faster burn rate than the first or second. When you get to some loads you have it install timing buffers/delays.
Now with that said, I will also tell you there are modern powders that will hold max pressure long enough to hose a brand new case, (no matter who made it) to the point where the primer will fall from the case when you open the bolt. The primer will not be blown nor will the case be split. And no it is not made by Hornady.
The duplex and triplex were some of Uncles ideas mainly to speed up AP rds in the 30-06 and 7.62x51. The reason it was pulled and stopped was some of the ammo was found being used in gas guns, and the reliability of the weapons suffered there after, with constant use. Lots of guys liked them as they were much flatter shooting across the board.

 

[EddieNFL]

A lot of people point bullets, and that seems like a bigger hassle. Is it "needed"? No, but it certainly provides a performance gain.

That's a little apples and oranges. At worst, you may deform a few bullets and decrease performance. Make a mistake blending and they may call you lefty, or one-eyed Jack, or a good man who will be missed.

 

[turbo54]

That's a little apples and oranges. At worst, you may deform a few bullets and decrease performance. Make a mistake blending and they may call you lefty, or one-eyed Jack, or a good man who will be missed.

I totally appreciate where you're coming from.

However, to be fair, the same thing can be said about reloading in general... Grab the jug/bottle of H110 instead of H414 to charge your'06 case with 50gr and you and your rifle aren't long for this world.

Still, I understand where your coming from; it has merit, and is why I haven't tried experimenting.

 

[EddieNFL]

Still, you're talking about a mistake versus an intentional act.

 

[logancummins338]

Im sure you could get by, but honestly, you will just be splitting hairs, you wouldnt gain much, and then your left with the question, "is this act of curiosity really worth smoking my gun?? And putting myself in danger??"

 

[Fuzzball]

"I'm interested in having an intelligent discussion about mixing/blending powders."

Okay, lets do that. What you're hoping for is a way to make a 'new' powder that improves on existing powders. Given that as a hopeful dream, who seriously thinks our powder makers are just too dumm to think of what you seek and believe the rest of us can klunge up some magic potion that will exceed the best those poor boobs who make their living with powders can accomplish? Given the vast range of cannister powders on the market today I can't imagine how anyone who actually understands the problems inherent in such a mix could imagine he might safely mix powders at home to any advantage at all. Call me a smuck.

I'm not intelligent enough to wrap my mind around how a reloader carelessly using the wrong powder is supposed to reconcile deliberately mixing powders in a blind experiment.

 

[Sniper Uncle]

Very interesting thread. It would be nice to be able to figure out how to do this safely. I personally don't have enough knowledge yet to do it, but think I might pursue learning more in this subject. I was reading the paper done by Chris Long on Optimal Barrel Time, and it seems that if one could safely mix certain powders successfully, or develop safe duplex/triplex loads, one would stand a better chance of successfully maxing velocities while keeping pressures under control, and at the same time matching a pre-calculated target Barrel Time. This could really be a game-changer.

 

[DIBBS]

Perhaps the powder manufacturing companies have experimented with this and could provide some results. Similar burn rates, starting low, you're probably OK. I've mixed different lots of the same powder to make my own lot, but the older I get, the LESS I wanna fool with mother nature. I just don't want to have a catastrophic failure, and there's soooo many different powders out there already....why bother taking a chance.

 

[savageshooter623]

There are so many different powders out there that im sure could fit your application. Like everyone said, what difference could you really expect if you were successful? Odds are you would be fine if you mixed like powders, but id atleast prefer the repeatability of one powder. That can even varry lot to lot. Now throw another powder in the mix and now at the very least you have 3 variables intead of one as far as powder goes. Risk and reward.

 

[turbo54]

"I'm interested in having an intelligent discussion about mixing/blending powders."

Okay, lets do that. What you're hoping for is a way to make a 'new' powder that improves on existing powders. Given that as a hopeful dream, who seriously thinks our powder makers are just too dumm to think of what you seek and believe the rest of us can klunge up some magic potion that will exceed the best those poor boobs who make their living with powders can accomplish? Given the vast range of cannister powders on the market today I can't imagine how anyone who actually understands the problems inherent in such a mix could imagine he might safely mix powders at home to any advantage at all. Call me a smuck.

I'm not intelligent enough to wrap my mind around how a reloader carelessly using the wrong powder is supposed to reconcile deliberately mixing powders in a blind experiment.

There it is... was honestly amazed how long the thread lasted before mommy arrived to tell us how stupid and careless we are.

To directly address your point (which I already did above but you missed or ignored it), does it compute in your brain that every cartridge under the sun has an optimal powder available off the shelf? There are tens of thousands of cartridges, and only a few hundred available powders, plus as mentioned prior, a LOT of overlap due to competition in the marketplace...for example IMR4350, H4350 and AA4350.

No, we (and I) don't think the powder manufacturers are too "Dumm" to blend the proper chemistry to optimize any given cartridge. It's a question of marketability. How much 264WM-optimized powder would they sell? Not much.

On the other hand, they'd sell a shit ton of 223, 308 and 30-06 optimized powders....which is why this topic of blending has not mentioned such mainstream cartridges-because they're covered.

 

[turbo54]

Perhaps the powder manufacturing companies have experimented with this and could provide some results. Similar burn rates, starting low, you're probably OK. I've mixed different lots of the same powder to make my own lot, but the older I get, the LESS I wanna fool with mother nature. I just don't want to have a catastrophic failure, and there's soooo many different powders out there already....why bother taking a chance.

The liability is HUGE. No way in sam hell is a powder manufacturer going to give you/me the straight dope on blending. They're going to say "NO! DON'T DO IT!!!!"

In this litigious society we live in, it's amazing we still even have companies making products like this!

 

[Sniper Uncle]

There it is... was honestly amazed how long the thread lasted before mommy arrived to tell us how stupid and careless we are.

To directly address your point (which I already did above but you missed or ignored it), does it compute in your brain that every cartridge under the sun has an optimal powder available off the shelf? There are tens of thousands of cartridges, and only a few hundred available powders, plus as mentioned prior, a LOT of overlap due to competition in the marketplace...for example IMR4350, H4350 and AA4350.

No, we (and I) don't think the powder manufacturers are too "Dumm" to blend the proper chemistry to optimize any given cartridge. It's a question of marketability. How much 264WM-optimized powder would they sell? Not much.

On the other hand, they'd sell a shit ton of 223, 308 and 30-06 optimized powders....which is why this topic of blending has not mentioned such mainstream cartridges-because they're covered.

Turbo, you are 100% correct on several scores here. Add to that, take Reloader 33, which was made specifically for the 338 Lapua Magnum. I have a 34" barrel on mine, and if you follow Chris Long's school of thought on Optimal Barrel Time, then the Reloader 33 does not find it's full potential, as you have so scale back on the charge to find your optimal node. What if you could place a small amount of another powder in the cartridge, as some of you are talking, and control the pressure, but regain the velocity and still satisfy the OBT? I would love it, and I will continue to research this idea. I am not brave enough to test it without doing more research, but I want to know the answer, so I shall pursue it farther.
Point is, the powder maker crafts a specific duty powder, but they can't make it specific to my gun, as my gun is different enough from mainstream guns to require a different "blend." In fact, I found that Reloader 50 should get me better velocity and lower pressure than Reloader 33, but it still is difficult to get that optimized for OBT.
Please keep discussing this thread, and share your thoughts, everyone, and ignore the ignorant ones who want to flame you. I for one want to find answers to this question, and do so safely. I believe there is a way to do that.
Tim

 

[Greg Langelius *]

Well, after several decades of handloading, I still think it's a good idea to let the village idiot find out where the minefields reside. Each of us has a uniquely ideal use.

I find more than enough explored avenues already exist which allow me to achieve my goals. I also find that as I get older, I have less and less time available with which to pursue perfection; adequacy has a quality that turns out to be surprisingly adequate all by itself. Perfection, besides being pretty much unattainable, is highly overrated, especially when 'adequate' gits 'er done just fine. Add to that the simple fact that components are currently in short supply, and I'll prefer to expend my limited supplies on experimentation in times of greater abundance.

To each, their own...

Greg

 

[waste_knot]

You can look at the MSDS sheets for powders and find the composition.
RL 17 is just >80% Nitrocellulose and <13% Nitroglycerin with some binders.
RL 15 is Nitrocellulose >80% Nitroglycerin <8% Diphenylamine <2%
It's important to note that a given mass of the same composition propellant will give the same volume of gas. It is a direct cemical conversion of solid to gas. Don't confuse peak pressure with volumetric gas pressure. A pound of NG produces a fixed amount of gas. Problem is it produces it at 6 miles per second which is well into detonation velocity. Equating this to internal ballistics would mean the entire gas pressure would be produced in micro seconds and the chamber would exceed 60ksi before the bullet started to move. This is where burn rate becomes a factor vs bullet mass.
All this stuff dissolves in acetone so you could find your mix and re-extrude it is the shape you want.

 

[Sean the Nailer]

I'm only going to say a few things, then continue reading as this thread progresses:

There is some incredibly interesting points and views on this thread.
There are a few 'insanely dangerous' points on this thread. To which, I know I wouldn't think twice about avoiding them, but "you can do it, go ahead! Don't forget to take video".
There are also some points that (as yet) seem to be missing.
-such as the surface area versus the perforations of the kernals of extruded powders is the main burn characterizing point.
-also the 'blending' of powders that is done to make FGMM, for instance.
--as I understand it, they aren't controlling the 'burn rate' near so much as the "pressure created", or something along that sort.

Now, all these points being considered, what is the actual intent in the long run? This being said, what lab analysis, scientific measuring devices let alone formula/statistician, and benchmark test equipment (Universal receiver?) are you using, to SAFELY attain your goal?

I'm not saying in any way "don't do it". Nor am I mothering anyone into indecision. What I am asking is, to what end, and extent, is this going? And how?

 

[nso123]

This is an interesting discussion. I have known a guy that loads duplex and triplex loads, and has done so for years. He swears by it, and claims that he has never had a problem. Is he good, or lucky? I suspect a little bit of both. It would be nice if someone with experience from a powder manufacturer would chime in and maybe explain why they don't do it, or if they do it in some other way that we are not aware of.

 

[Niles Coyote]

Correct. My suggestion was that different burn speed characteristics are a result of the different size of the kernels, not the chemical makeup, which explains why the Hodgdon extreme lineup of powder gets larger and larger all the way up the line. This decreases the surface area/volume ratio, slowing the burn.

I have thought this as well.

Watching with interest.

 

[turbo54]

You can look at the MSDS sheets for powders and find the composition.
RL 17 is just >80% Nitrocellulose and <13% Nitroglycerin with some binders.
RL 15 is Nitrocellulose >80% Nitroglycerin <8% Diphenylamine <2%
It's important to note that a given mass of the same composition propellant will give the same volume of gas. It is a direct cemical conversion of solid to gas. Don't confuse peak pressure with volumetric gas pressure. A pound of NG produces a fixed amount of gas. Problem is it produces it at 6 miles per second which is well into detonation velocity. Equating this to internal ballistics would mean the entire gas pressure would be produced in micro seconds and the chamber would exceed 60ksi before the bullet started to move. This is where burn rate becomes a factor vs bullet mass.
All this stuff dissolves in acetone so you could find your mix and re-extrude it is the shape you want.

Great post. It hadn't dawned on me the MSDS would provide some details on composition. Also, you've succinctly stated why burn speed is critical.

I'm not sure if you were joking or not about dissolving powders together and re-extruding the new mixture or not.... . I'm not sure I'm interested in getting that deep into it, though I do have a spaghetti extrusion machine!

Two things about that, though: I thought most powders were made by dissolving the nitrocellulose/nitoglycerine in ether, not acetone?

Also, at least in regard to Hodgdon extreme powders, you'd be mixing the burn retardent coating INTO the mix. Gotta imagine that would affect things. My understanding is that's the deal with Reloader 17. The burn slower stuff is mixed throughout instead of just coated.

 

[turbo54]

I just reviewed the MSDSs for Hodgdon benchmark, 4895, Varget, 4350, 4831, h1000, Retumbo and 50bmg.

As far as the msds is concerned, benchmark, 4895, Varget, 4350 and 4831 are identical.

H1000 and h50bmg are the same as one another but differ slightly from the faster powders.

Retumbo is it's own thing, with extra compounds to include KNO3 (potassium nitrate). I guess that explains why they offer both Retumbo and H1000, which are damn similar. Also, Retumbo has a unique scent when burned.

 

[Bill Larson]

near same discussion long ago over on benchrest central......nearly identical replies.....alot of guys admitted to mixing.Most common was N133-N135 to get custom...homemade 134.......
Duplex loads are common with black powder cartrdge shooters.......

 

[Fuzzball]

"No, we (and I) don't think the powder manufacturers are too "Dumm" to blend the proper chemistry to optimize any given cartridge. It's a question of marketability. How much 264WM-optimized powder would they sell? Not much."

Given your convictions of personal reloading and marketing "wisdom", I'm astonished you would seek reassurance for what you wish to do from anonymous web posters with far less knowledge than yourself. And "intelligent discussions" don't start with a prohibition of opposing views.

Given that you suppose there is or can be an "opimized powder" for any cartridge confims my original suspicion that you know far less about powders and reloading than you think.

 

[TheRedHorseman]

Two things about that, though: I thought most powders were made by dissolving the nitrocellulose/nitoglycerine in ether, not acetone?

If it will dissolve in diethyl ether, it will almost certainly dissolve in acetone.

 

[twinky]

Only been around one project that involved mixing powders, and that was for a 338 Rem. Ultra Mag. Re-25 seemed too slow to get optimal speed, Re-22 showed pressure before getting target speed. So, they got mixed. Some were one first, then the other on top, others mixed. When it was all said and done, nothing was gained, and IIRC, he went with Re-25.

 

[Unknown]

The biggest problem I can think of is maintaining either the separation in a stacked load, or maintaining the same mix without any settling out in a mixed load. If either one happened, consistency would go out the window. Once you loose the consistency, you would be better off staying with only one powder that would maintain consistency.

 

[Brandon05_88]

I damn near mixed 50/50 H4895 and Varget when looking for a load for my Noveske. Couldn't get velocity I wanted with Varget without an uncomfortable amount of crunch. I hit pressure with H4895 before I even reached 100% fill. I was going to weigh 250 grains H4895 then 250 grains Varget and mix together for a small OCW. I figured start low, work-up and it'll be peachy right?

As a last effort, I loaded my rounds to 2.265" and re-tested H4895 and Varget. I found the load with H4895 after extending OAL.

I honestly don't think 2 rifle powders with similar burn rate, manufacturer and kernel shape would be a problem. Mixing ball and extruded to fill voids seems reasonable. The whole topic is interesting, but I'd test it in a bolt gun.

 

[mudpig]

Several years ago I bought a book on CD from one of the guns magazines entitled Gibbs' Cartridges and Front Ignition Loading Techniques. I bought it specifically because I wanted to build a 270 Gibbs, but the other side of the story was his interest in duplex loadings. He had fewer powders back then, but I think his idea was the same as our goal now. To maximize the max pressure duration and increase bullet velocity. He also claims that his front loading technique reduced barrel errotion and recoil. His method was to install a flame tube inside the case for approx 2/3 the length of the case (similar to military howitzer shells). This would start the powder burn behind the bullet, not at the base of the case. The powder would then burn toward the base of the case. He claimed this reversed burn direction would reduce recoil because you were not propelling the powder charge and the bullet down the bore and lacking the propelled powder, this helped reduce throat errosion. As for maximizing max pressure duration, he surmized that peak chamber pressure was not the moment the bullet left the barrel, but prior to that point. He decided to duplex load his front loading technique. His technique was to load a faster burn rate powder (3031) into the base of the case and fill the remainder with 4831 to a total of 100 percent load density so there would be NO mixing of the powder. He worked slowly from a known safe charge of 100 percent 4831 to a mix by weight. He'd subtract 5 percent 4831 and add 5 percent of 3031, up to a max of 10 percent if memory serves me right. His thought process was that the primer with flash tube would ignite the 4831 first and this would push the bullet down the barrel and the pressure would start to drop, then the burn would reach the faster 3031 powder and this faster powder would maintain the previously reached pressure through more of the expansion period as the bullet passed down the barrel. His claims were 100 to 200 more fps using his technique. His book was a good read and got me amped up to try it. I got the brass and the tubes, all the tap and dies and then I got deployed overseas and kind of blew out the fire. Stuff has been sitting on my reloading bench since. Still intend to give it a try, just haven't had the time or motivation lately. His book is still advertised on CD from time to time in a few of the pubs.

 

[mudpig]

Here....I found were you can get a copy of the book if interested.

http://www.riflemagazine.com/catalog/detail.cfm?ProductID=820