Mixing BP granulations & even good brands

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TexasMac
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Mixing BP granulations & even good brands

Post by TexasMac » Sun Apr 04, 2021 8:56 pm

I recently started a couple of thread on ladder testing that turned out unexpectedly to be a controversial subject. So I’m on a roll and figured I’d start another thread, one I expect will definitely be controversial.

Many years ago, I purchase 3 cases (45lbs) of Swiss 1.5Fg. They were all different lots. So rather than have to do load development again when changing from lot-to-lot, I decided to mix them all together. I used a large aluminum pot & mixed it all real well, then poured it back into the original bottles. I mentioned this to a few shooters & also casually commented about it in some forum threads. The common response is “you can’t do that or “you shouldn’t do that”. When I asked why not the response was usually the same, “you just can’t”. No one could offer a good reason why it wasn’t a good idea, at least no one that made sense to me. That batch worked out great and lasted for several years until a few months ago.

So, in addition to smaller quantities of 1.5Fg, 2Fg and some 3Fg that I’d accumulated over a few years, some won at match, etc., I picked up a case of Swiss 1.5Fg. It all amounted to 45lbs of 11 different lots. I certainly did not look forward to having to do load development with each lot. And after testing the density of the newer powder and finding most of it was fluffier than the old stuff & of course different from lot-to-lot, I decided to do the same thing again. I’m guessing here but the custom mix is likely equivalent to what one might call 1.75Fg if there were such a grade.

So now I have a custom mix that has worked well for several matches in my Browning & Sharps & will last for several years. This technique removes a significant factor form the load development equation.

BTW, I just had a conversation with a good friend & BPCR shooting partner. He’s got several bottles of OE 1.5Fg, several of Swiss 1.5Fg and a bunch of Swiss 3Fg, all totaling 33lbs. We discussed mixing it all together for the same reason noted above. He’s considering it.

Wayne
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TexasMac
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Re: Mixing BP granulations & even good brands

Post by TexasMac » Sun Apr 04, 2021 9:19 pm

After rereading this I see my typing skills leaves a lot to be desired,
Wayne
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axman
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Re: Mixing BP granulations & even good brands

Post by axman » Sun Apr 04, 2021 9:24 pm

Sounds like a good way to be consistent for a long time of loading.

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Re: Mixing BP granulations & even good brands

Post by WVsmoke » Sun Apr 04, 2021 9:36 pm

Texasmac,
I would be more concerned with mixing powders of different granulations more than powders of the same granulation. The physics involved will allow more weight for a set volume of mixed granules than a volume of the same size granules. Therefore the amount of powder in a given volume would change as to the composition of the grain sizes as related to each other. This would require thorough mixing continually through out the process of mixing and re-filling individual bottles, and before dispensing. The grains would start to “sort out” whenever handling or moving, so when dispensing you may have differences in wt and volume. It may be like having a lot of “dust” in the bottom of your pound of powder.
On the other hand it may work great.... :D Allan
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TexasMac
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Re: Mixing BP granulations & even good brands

Post by TexasMac » Sun Apr 04, 2021 10:49 pm

WVsmoke wrote:
Sun Apr 04, 2021 9:36 pm
Texasmac,
I would be more concerned with mixing powders of different granulations more than powders of the same granulation. The physics involved will allow more weight for a set volume of mixed granules than a volume of the same size granules. Therefore the amount of powder in a given volume would change as to the composition of the grain sizes as related to each other. This would require thorough mixing continually through out the process of mixing and re-filling individual bottles, and before dispensing. The grains would start to “sort out” whenever handling or moving, so when dispensing you may have differences in wt and volume. It may be like having a lot of “dust” in the bottom of your pound of powder.
On the other hand it may work great.... :D Allan
Allan,

Good point and I agree that the 3Fg & possibly the 2Fg will tend to settle to the bottom of the mixing tub and in the bottle. Due to that concern, when refiling the bottles I continue to mix the stuff in the pot and later make a point of aggressively shaking & turning the bottle upside down prior to pouring it into the dispenser. Once the loading is complete any remaining in the dispenser is poured back into the bottle. BTW, even when it's all one grade I do the same to distribute the "fines" throughout the mixing tub & subsequently in the bottles.

Wayne
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TexasMac
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Re: Mixing BP granulations & even good brands

Post by TexasMac » Sun Apr 04, 2021 11:13 pm

I should mention that when measuring velocity I routinely get SD's in the 3 to 2 range and have hit an SD of 1 a few times. Therefore I have to assume the powder mix has not had an significant affect. I should also point out those results were with the old mix of 3 different lots of Swiss 1.5F. I have not measured velocities after mixing the recent powder of various granulations. I plan to do so. I have shot a master score using it in a recent match so it seems to be working great so far.

Wayne
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DAVE ROELLE
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Re: Mixing BP granulations & even good brands

Post by DAVE ROELLE » Mon Apr 05, 2021 5:47 am

I knew ya could do it Wayne 😉

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Re: Mixing BP granulations & even good brands

Post by John Bly » Mon Apr 05, 2021 7:09 am

I've mixed different lots of powder. I had accumulated 7 or 8 lbs of 1 1/2F won at matches that were of several lots. I bought 10 lbs of a new lot and mixed them all together. I mixed them outside in a metal bucket with a wooden paddle. It worked out well. I would not mix different granulations. If I had no use for them I would trade them off at a match to someone who would use them.
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Re: Mixing BP granulations & even good brands

Post by George Babits » Mon Apr 05, 2021 7:50 am

About 15 years ago I did a lot of experimenting with small batches of mixed granulations. I'm not sure what prompted the experiments, but I suspect that it was after a lot of correspondence with Bill Knight. Anyway, for the testing I used a 420 grain flatnosed bullet and put well over 1000 rounds of 45-70 through the chronograph with my rebarreled original Sharps. I mixed various combinations of Fg, FFg, and FFFg and found that you could get any velocity you wanted by carefully combining the various granulations. The SD for each combination was almost always in the single digits. The whole idea was to maintain the same "amount" of powder in the case, hence the same compression. This seemed to work well in small batches, but the biggest problem was maintaining overall consistancy of the mechanical mix in a large batch. The whole project gave me an excuse to do a lot of shooting that summer. The reality, however, is that it was a bit of a PITA when you could produce the same results with more or less compression and a single granulation of powder.

George

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Re: Mixing BP granulations & even good brands

Post by bpcr shooter » Mon Apr 05, 2021 11:04 am

Ive done it with smokeless to have one huge lot. I found a load and have been shooting that for a few years now. I cant see why it wouldnt work, or what ill effects it would have, other than having to most likely make a new load

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Re: Mixing BP granulations & even good brands

Post by mdeland » Mon Apr 05, 2021 1:38 pm

Wayne,did the fines increase significantly with each mixing ?

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Re: Mixing BP granulations & even good brands

Post by DaveC » Mon Apr 05, 2021 3:02 pm

I worked for a company that made safety fuse, Coast Fuse Co., and we had to blend black powder for a burn rate in the safety fuse of 120 seconds/yard, plus or minus 10%. The burn rate was checked by filling lead tubes with the blend, extruding the tubes, cutting them in 1-foot lengths, and burning them in a trough cooled with water to a standard temperature. The burn rate in the fuse could be predicted from the burn rate in the lead tubes by calculation.

The powder was from GOEX back then, and I think they were still in Moosic, PA. They had only recently bought the operation from DuPont. It came in 25-lb bags (two to a case), and was of two speeds, “fast” and “slow.” We checked the speeds in the lead tubes, calculated the weight needed of each from a burn rate curve that DuPont had developed, and blended (IIRC) 1500 lbs at a time in a large wooden barrel in a barricaded house at the bottom of a ravine.

They’d spin the barrel for four hours or so, stop it and get us samples. With experience, we got pretty good at figuring whether the powder needed another bag or two of “fast” or “slow,” or whether it was only necessary to spin the barrel another couple hours.

The granulation of both powders was very similar, around 4f or finer, but it was pretty obvious when the mixture wasn’t “right” for the safety fuse. It may be that burning under pressure in a cartridge or muzzleloader evens out the burn rate so that the proportions and homogeneity of the mixture isn’t as important as it is in the slight excess pressure that safety fuse operates at. But I am surprised that mixing the different granulations in a big aluminum pot turned out so well. How long did you mix it, and by what method?

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Re: Mixing BP granulations & even good brands

Post by TexasMac » Mon Apr 05, 2021 5:35 pm

mdeland wrote:
Mon Apr 05, 2021 1:38 pm
Wayne,did the fines increase significantly with each mixing ?
Mike,

I'm not sure what you're asking. The following is how I mixed all the 45 lbs. I used two large metal pots, one significantly larger than the other. I split all the powder into 3 batches which was easy since I had 33lbs of 1.5F, 6lbs of 2F & 6lbs of 3F. I them mixed extremely well 1/3 or 15lbs of it all (11/2/2) in the smaller pot. During all the mixing I made a point of rotating the stuff on the bottom to the top. Then all 45lbs was mixed together in the larger pot. I filled the individual bottles from the final mix using a long handle aluminum scoop & funnel & continued to mix it all while filling the bottles. The continues mixing was to ensure the 2F & especially the 3f did not settle to the bottom of the mix at any time. Whatever fines were in the original bottles was certainly thoroughly mixed throughout the whole batch. Since the batch now contains 13.3% 2F and 13.3% 3F I guess one could call the 3F fines. If the mixing process itself created more fines than I have no idea how to measure it and I really don't care.

Wayne
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Re: Mixing BP granulations & even good brands

Post by mdeland » Mon Apr 05, 2021 7:15 pm

I'm asking if significantly more fines where being produced with the mixing from grain fracture ?

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Re: Mixing BP granulations & even good brands

Post by TexasMac » Mon Apr 05, 2021 7:23 pm

mdeland wrote:
Mon Apr 05, 2021 7:15 pm
I'm asking if significantly more fines where being produced with the mixing from grain fracture ?
Mike,

I have no idea and I'm really not concerned if the percentage of fines increased. If I was concerned I have no way to determine if more were created due to not knowing the percentage of fines prior to mixing.

Wayne
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