Position Sensitive Powders

[Pirate69]

I have seen a number of powders mentioned as being position sensitive. Has a list of position sensitive powders ever been assembled? If not, please chip-in the name of a powder that you feel is position sensitive. Thanks.

[Wayne S]

It's as much to do with the Vol. of powder to the case capacity , or "loading density" expressed as a %, that to say a certain powder ; ie Unique, 2400, RL-7,748, ect. is a position sensitive. And any low loading density load can be improved on by using a filler such as "Dacron" or a "shot buffer" like PSB, or simply by raising the muzzle before every shot.

[Pirate69]

thanks

[Gleedaniel13]

Unique, 2400, RL-7,748, ect. is a position sensitive. And any low loading density load can be improved on by using a filler such as "Dacron" or a "shot buffer" like PSB, or simply by raising the muzzle before every shot.

I agree with this one.

[jonk]

I disagree. I have never found unique, 2400, or any of the fast pistol or shotgun powders to be position sensitive or need filler in the least.

Position sensitive powders are usually reduced load medium to slow rifle powders. Eg: 30 gr of 4895 really requires a dacron (or similar) wad in 30-06 or you get great velocity variation.

[1johnlb]

Jonk is right, unique and 2400 are not position sensitive.

[Larry Gibson]

Jonk is right, unique and 2400 are not position sensitive.

Disagree. Both powders certainly are in some cartridges with some bullet weights. All powders can be position sensitive when load density is small for the powder, especially if shooting at angles larger than 45 degrees. They also can be position sensitive if raised up from varying field carry positions to shoot; muzzle carried up one time and muzzle down the next, etc.

Larry Gibson

[1johnlb]

JUST GOING TO SCHOOL.

[BruceB]

Disagree.

All powders can be position sensitive when load density is small for the powder

Larry Gibson

I agree with Larry 100%.

I performed ACTUAL CHRONOGRAPHED TESTS in many different cartridges/calibers.

Direct comparisons between loads that were identical except for dacron/no dacron revealed that even the powders reputed to be NOT sensitive to position in the case WERE, in fact, position-sensitive to a degree.

WITH Dacron, the velocities were more-uniform and extreme spreads and standard deviation were both smaller.

Ergo, Larry is correct, according to my experiments.

[1Shirt]

Yep, agree with Bruce and Larry. I always use a dac filler when I shoot 2400 in rifles from "the Load", upwards. Have never used a filler w/Unique, but when I use it in a rifle, I tip the rifle up before each shot.!
1Shirt!

[williamwaco]

One can never prove that a powder is always or never position sensitive because you can never try all possible combinations.

That said, I have chronographed 9.0 grains of Unique in the .30-30 with 150 grain cast and in the .38-55 with 265 grain bullet.
Five shots each with the cartridge case pointed down and shaken, the cartridge case up and shaken and the cartridge case held level and shaken back and forth.
There was no filler.

In both tests the difference in the average velocity between forward, center, and back positioned powder was less than the difference between individual rounds in each five shot string.

[303Guy]

Interesting test results. I am under the impression that the 30-30 and smaller cases are be less sensitive to powder position. In doing these test, it would be interesting to note what primers are being used and what there power is. I use Federal primers because they are reputed to be quite good and are quite sensitive (soft cups or something) and they have the lowest power which apparently is good for accuracy (possibly because they move the bullet less before ignition gets going?) They also make reading relative pressure easy.

[1johnlb]

" less sensitive"

But still sensitive.

With good load techniques and correct said powder percentages along with proper shooting techniques, position sensitivity can be made none existent or at least controlled on so called non position sensitive powders.

OP's question was which powders are position sensitive?
All powders can be position sensitive

[303Guy]

But some more so than others. I suspect that some rifles will show no apparent sensitivity to a particular power due to compensating barrel harmonics. The sensitivity may then show up at longer ranges? Anyway, I always use a filler of powder positioner (Dacron). I also use Dacron when not needed as in near full case to stop powder spilling out should a boolit get pulled out on extracting an unfired round.

[williamwaco]

Interesting test results. I am under the impression that the 30-30 and smaller cases are be less sensitive to powder position. In doing these test, it would be interesting to note what primers are being used and what there power is. I use Federal primers because they are reputed to be quite good and are quite sensitive (soft cups or something) and they have the lowest power which apparently is good for accuracy (possibly because they move the bullet less before ignition gets going?) They also make reading relative pressure easy.

CCI large pistol #300.

[35remington]

Figure that all powders are somewhat position sensitive and you'll save yourself some aggravation. After chronographing your own loads with powder forward and powder rearward, you can judge the relevance of the observed velocity variation.