PDA

View Full Version : Powder charge variation and the Brazil Nut Effect



Clusterfrack
05-10-2018, 01:46 PM
I have been using Nobel Sport Prima V for minor power factor 9mm loads, and noticed some significant variation in charge weight (up to 1 grain in a 3.5 gr charge). At first, I thought it was just that the powder didn't meter well in the Dillon powder measure. But that wasn't the case. Charges were very consistent for 100's of rounds, but fluctuated up and down steadily.

Inspection of the powder hopper revealed stratification of grain sizes, with the largest grains on top. This is a recently discovered phenomenon in the physics of granular media called the Brazil Nut Effect (https://en.wikipedia.org/wiki/Granular_convection). Counterintuitively, the largest, heaviest particles end up on top. This is why rocks keep sprouting in plowed fields. Of course, powders with a very uniform grain size (e.g. Titegroup) wouldn't have this problem.

My solution is to mix the powder with a chopstick when it's half used, and then again when I fill it. I also mix the powder in the jug before pouring. My charge weights have been spot on so far.

https://uploads.tapatalk-cdn.com/20180510/4980c28a615d6b7b54620aa14a0b6c2f.jpg

SecondsCount
05-10-2018, 05:50 PM
Wow! That is pretty interesting. I use WSF or Vit N320 and have never seen this issue but it is a good thing to watch for.

Clusterfrack
05-10-2018, 07:30 PM
Here’s a better picture:

https://uploads.tapatalk-cdn.com/20180511/72a32bdd29c0f9a2fb454f237c12b075.jpg

willie
05-10-2018, 08:37 PM
In 50 years of reading reloading materials, I'm seeing this occurrence for the first time. Good report!

pangloss
05-10-2018, 08:59 PM
It happens with loose tea leaves too. By the time I get to the bottom of a can of tea, the pieces are so small that it's essentially dust. I never considered the broader implications though. Good to know.

Sent from my Moto G Play using Tapatalk

GuanoLoco
05-10-2018, 09:23 PM
I loaded a lot of PrimaV and had taken to shaking up each jug carefully, then manually throwing many priming charges.

Looks like US availability is probably done, moving to CSB-1M next. If s like the ETR-7 / (I think CSB-1) from Expansion Industries (who went bust) but with a smaller flake. ETR-7 was my fav powder to date, and prelim testing shows CSB-1M is as good or better.

H&KFanNC
05-10-2018, 09:45 PM
Very interesting and good information. Thank You!


Sent from my iPhone using Tapatalk

Clusterfrack
05-11-2018, 12:37 PM
I was able to get quite a bit of Prima V, but availability has been intermittent. I like N320 as well, but it's expensive.

Prima V feels really soft in comparison to Titegroup, and is not nearly as hot or dirty. The dynamics of my PrimaV load in my Shadows feels pretty close to perfect for me (e.g. 1.54s Bill Drill). I'm getting great accuracy as well. So, I'm going to continue to use it until it's gone. Hopefully, more will arrive from France...
GuanoLoco, where do you buy CSB-1M?

GuanoLoco
05-11-2018, 02:42 PM
I was able to get quite a bit of Prima V, but availability has been intermittent. I like N320 as well, but it's expensive.

Prima V feels really soft in comparison to Titegroup, and is not nearly as hot or dirty. The dynamics of my PrimaV load in my Shadows feels pretty close to perfect for me (e.g. 1.54s Bill Drill). I'm getting great accuracy as well. So, I'm going to continue to use it until it's gone. Hopefully, more will arrive from France...
GuanoLoco, where do you buy CSB-1M?

https://hi-techammo.com/products/csb-1m-pistol-powder-comes-with-loading-data

Owner is sitting on about 1000 lbs he wants to move; price is right. I’ll probably do a max order / hazmat fee soon and split with local friends.

What I liked about CSB-1 / -1m vs. PrimaV - Cleaner, Meters much more consistently.

Clusterfrack
05-11-2018, 04:02 PM
How is the burn rate? Or perceived “softness”? N320 and Prima V feel softer to me than Titegroup.

Hambo
05-11-2018, 04:09 PM
This is a recently discovered phenomenon in the physics of granular media called the Brazil Nut Effect (https://en.wikipedia.org/wiki/Granular_convection). Counterintuitively, the largest, heaviest particles end up on top. This is why rocks keep sprouting in plowed fields. Of course, powders with a very uniform grain size (e.g. Titegroup) wouldn't have this problem.


Dude, that is so cool and good to know. :D

Jim Watson
05-11-2018, 04:33 PM
That is interesting to know, in a scientific hypothetical way.
Hypothetical, because I am not going to add powder stratification to my other loading concerns. Bye, bye Prima V.

Spartan1980
05-11-2018, 07:50 PM
I loaded a lot of PrimaV and had taken to shaking up each jug carefully, then manually throwing many priming charges.

Looks like US availability is probably done, moving to CSB-1M next. If s like the ETR-7 / (I think CSB-1) from Expansion Industries (who went bust) but with a smaller flake. ETR-7 was my fav powder to date, and prelim testing shows CSB-1M is as good or better.

I almost jumped onto the Prima V bandwagon and after seeing this I'm sure glad I didn't. There was a cult like following on the Enos forum for awhile right after it became available. The price on that first lot was sure right too but I stuck with my e3 for gamer loads. For handguns I could get by with e3 for the gamer stuff and BE-86 for other loads for more serious applications.

Clusterfrack
05-11-2018, 07:52 PM
It’s tempting to submit a paper on this to Journal of Physics: Condensed Matter, just to see the editor’s response. [emoji3]

GuanoLoco
05-11-2018, 10:21 PM
I am not hating on PrimaV, but I do take exception when availability becomes an issue.

It’s still way better than Titegroup, or any of the other powders that I have tested.

GuanoLoco
05-12-2018, 08:18 AM
How is the burn rate? Or perceived “softness”? N320 and Prima V feel softer to me than Titegroup.

With all due respect, I have no idea what you are asking. I only perceive differences due to bullet weight and powder burn rate. I think the whole ‘soft shooting’ thing, based on my own testing - on the timer + perception - and many, many 10’s of thousands of rounds - is hoo-hah.

At this point I am interested in 124gr bullets and powders that are fast-burning, cheap, clean, available, decent bulk (double charge should be obvious/not allow easy bullet seating), consistent (low velocity spread at > min Power Factor), temperature-insensitive and that meter well, not necessarily in that order.

Clusterfrack
05-12-2018, 10:32 AM
I agree about the "soft-shooting" hoo-hah--mostly.

I think there are 3 related factors: burn rate, bullet weight, and charge weight (for a given velocity) that affect the recoil impulse. Some powders just feel better to me, but I'll admit that it's probably pretty subjective.

And, I agree with your priorities as well. Right now, I'm really happy with Blue Bullets and Prima V or N320.

GuanoLoco
05-12-2018, 04:26 PM
If you fix power factor, then burn rate/charge weight is really one item. For a given bullet weight, and any of the ‘fast’ pistol powders, I’m not sure that burn rate differences are even perceptible in recopil.

I can’t justify N320 on price alone. PrimaV was available at a pretty compelling cost point for a while (13-$14 / 1.1 lb jug), especially with the deal where there was no Hazmat for 10+ jugs.

ACME has a pretty compelling bulk price for 124’s - $0.06 ea shipped for qty 12,000 (from memory). It is possible to do even better.

I just finished a 500+ rpund practice session where I was able to shoot GM-level scores on 3 different classifiers with 124gr bullets and a (not to be named) stupid fast powder that I am loading for $0.002 / charge for practice ammo. Regular powders are usually $0.01 / charge, and N320 probably $0.02 / charge. Cheaper ammo = more ammo for practice, and that matters.

I honestly don’t think recoil impulse was a relevant factor in my performance (or lack thereof).

cjb1911
05-13-2018, 06:46 AM
With all due respect, I have no idea what you are asking. I only perceive differences due to bullet weight and powder burn rate. I think the whole ‘soft shooting’ thing, based on my own testing - on the timer + perception - and many, many 10’s of thousands of rounds - is hoo-hah.

At this point I am interested in 124gr bullets and powders that are fast-burning, cheap, clean, available, decent bulk (double charge should be obvious/not allow easy bullet seating), consistent (low velocity spread at > min Power Factor), temperature-insensitive and that meter well, not necessarily in that order.

I just started using alliants new sport pistol. Meters and performs like n320, they also claim it was developed for coated bullets so it doesn't burn as hot as TG. I suggest you give it a try.

GuanoLoco
05-13-2018, 06:59 AM
I just started using alliants new sport pistol. Meters and performs like n320, they also claim it was developed for coated bullets so it doesn't burn as hot as TG. I suggest you give it a try.

I’ve heard about it - not a bad deal but I’m always looking for GREAT deals, then we buy in bulk and split.
https://www.grafs.com/catalog/product/productId/76148

The other one on my list to test if I get a chance is Shooter’s World Clean Shot / Lovex
https://shootersworldsc.com/clean-shot/
“Clean Shot is a canister form of Explosia bulk propellant D032-02.”
https://www.midsouthshooterssupply.com/item/00130cleanshot5/shooters-world-clean-shot-smokeless-powder-5-lb-by-lovex

If either is as good as the MAXAM CSB-1/CSB-1M I’d be thrilled.

I have great hopes for these next-gen powders.

cjb1911
05-13-2018, 07:06 AM
I'm also trying out wc244 winclean. It's basically 231 equivalent but cleaner(obviously). Midsouth is really promoting all the shooters world stuff right now. My chrono recently suit the bed, so I'm waiting on a magnetospeed to come in so I can do some serious load development.

GuanoLoco
05-13-2018, 08:17 AM
I tested and ruled out Win231 and WST - both were (surprisingly) reverse temperature sensitive, as often claimed on the interwebs. I had always written that off as nonsense, but velocity swung pretty widely up with chilled mags and down with heated mags.

SAWBONES
05-13-2018, 08:25 AM
I learned something new! Thank you.

nwhpfan
05-14-2018, 04:47 PM
I have been using Nobel Sport Prima V for minor power factor 9mm loads, and noticed some significant variation in charge weight (up to 1 grain in a 3.5 gr charge). At first, I thought it was just that the powder didn't meter well in the Dillon powder measure. But that wasn't the case. Charges were very consistent for 100's of rounds, but fluctuated up and down steadily.

Inspection of the powder hopper revealed stratification of grain sizes, with the largest grains on top. This is a recently discovered phenomenon in the physics of granular media called the Brazil Nut Effect (https://en.wikipedia.org/wiki/Granular_convection). Counterintuitively, the largest, heaviest particles end up on top. This is why rocks keep sprouting in plowed fields. Of course, powders with a very uniform grain size (e.g. Titegroup) wouldn't have this problem.

My solution is to mix the powder with a chopstick when it's half used, and then again when I fill it. I also mix the powder in the jug before pouring. My charge weights have been spot on so far.

https://uploads.tapatalk-cdn.com/20180510/4980c28a615d6b7b54620aa14a0b6c2f.jpg

Leave it to a scientist to "discover" what nut eating yahoo's have always known.... :)

Super77
05-14-2018, 08:38 PM
ACME has a pretty compelling bulk price for 124’s - $0.06 ea shipped for qty 12,000 (from memory). It is possible to do even better.

Regular powders are usually $0.01 / charge, and N320 probably $0.02 / charge. Cheaper ammo = more ammo for practice, and that matters.

Interesting, what do you do for primers?

GuanoLoco
05-14-2018, 09:56 PM
Interesting, what do you do for primers?

This is getting a little far afield from OP, I get with competitive shooter friends and we do bulk orders (100K+) to drive down price and split.

CCI’s for practice (cheaper and more available), Federals for match. I’ve mostly given up on the other primer manufacturers - too much variability / too hard / too many issues with availability, reliability, etc.

I spring my guns to run CCI’s reliably in practice - also, I’m running a DA/SA gun (Tanfo Stock 2) so I don’t have a 1911/2011 that hits primers with the authority of Mjolnir. Anything that will light CCI’s with > 99.x% reliability will light Federals no problem.

So...I can load practice 9mm for just under $0.08/ea, match for < $0.09 ea and that’s with range pick up brass.

I have decided that brass picking may not be the best for my time/knees/back, so I bought a 55 gal drum of 9mm range pickup brass at about $0.01 ea. (Probably half going rate). Sometimes I trade brass for brass cleaning services - I have a cement mizer that will wet clean 5 gallons / 9000 cases at a time and a pair of 1000 watt dehydrators for drying.

Powder - same thing. We go bulk, look for sales / discounts / shipping / hazmat, mazimize orders and split. My current practice only powder I conditionally took off someone’s hands at a stupid discount, worked up a load that I would never share but that has proven reliable and consistent at 126PF, and that costs me almost nothing (0.002 ea).

The bulk deals from ACME on bullets are pretty good but it is possible to do a little better.

A friend was asking the other day why I’m not negotiating and buying bullets in 100K+ qty and freighting it in. My normal buys are in the 10-30K range. It’s a good Q. I might do that next cycle.

A different bullet manufacturer asked if I wanted to be a reseller - hard pass - I’m doing this as a hobby and don’t really want the hassle, even if doing so might reduce my costs further.

I loaded and QC’d (case gauged) a couple thousand 9mm last night on the Mark 7/1050. Took a couple hours soup to nuts. Time is a thing too.

Edit: I’m a little picky on reloading QC: COAL < 1.120, Crimp to 0.378”, CCI primers seated to 0.008”+, pass Ben Stoeger Hundo Case Gauge. 20 throw averages of powder usually within a few 10ths of a grain of my target, and I check at least before and after every load session, power factor > 125, and more like 128-133 for match ammo.

willie
05-14-2018, 11:16 PM
WOW. You are serious about reloading.