New pound of powder question.....

[Fatelvis]

In the past, knowing I'll be shooting alot of rounds in highpower competition, I bought 4 - 1 lb canisters of RL15 of the same lot, because they didnt have a 5 lb. jug like I wanted. I just finished my first pound, and opened the second, and found that my previously set, (and proven correct setting) powder measure, is throwing a heavy charge, (by about 1.25 grain!). Now I know from past experience that powder, after opened, dries out over time, and gets lighter. (As in my first pound). My question is, do I go by weight, or volume, when using these next three pounds? Thanks a million!-

 

[Steve C]

Loading data is listed in grain weight of powder charge. If it was me and that 1.25gr puts the charge near or above the maximium listed in the load manuals I'd drop it back down to the previous load or below and check for accuracy. If the increased load was still safely below the maximum listed in the mauals I'd be tempted to try it out but you still need to check accuracy to see if its still there.

 

[armedandsafe]

ALWAYS measure smokeless by weight and blackpowder equivalents by volume. True BP can be measured either way.

Pops

 

[Fatelvis]

After reading Glen Zediker's "Reloading For Competition", he said something that really hit home, in relation to this subject.
Knowing that the freshly opened pound of powder is from the same lot as the last, I should NOT have changed the powder measure, to make the fresh powder dispension weigh the same. KNOW WHY? Because as the powder in the old canister got lighter, (because of moisture evaporation), the SAME thing will happen in the freshly loaded cartridges. So from now on, Im not changing my measure after finding a good, safe load. (As long as the fresh powder is from the same lot).

 

[yodar]

"moisture evaporation"

so solly. There is no moisture in powders. Nitrocellulose powders are made with nitric acid and sulfuric acid and water in that process would ruin it.

NO water is present EVER


The solvents in nitrocellulose powders are ether, acetone, and other ORGANIC solvents. They are all low molecular weight and dont contribute a great amount to the powder's weight .

However, these solvents do evaporate and they have a characteristics smell, some say like a doctor's office. That will TECHNICALLY make the powder lighter, definitely denser statistically, but I have never had a problem with powders as you describe.

Jug to jug, my tabulated loads are all repeatible.

Yodar

 

[Jim Watson]

A friend of mine had a similar problem. He loaded by weight, setting his measure as required for the new can of different density. Velocity was about 10 fps lower for the same weight but substantially less volume. Accuracy on target was good. Another guy here thought they were all the same and loaded with two lots of powder and mixed the rounds promiscuously. He was all over the target.

 

[Fatelvis]

[so solly. There is no moisture in powders. Nitrocellulose powders are made with nitric acid and sulfuric acid and water in that process would ruin it.

NO water is present EVER


The solvents in nitrocellulose powders are ether, acetone, and other ORGANIC solvents. They are all low molecular weight and dont contribute a great amount to the powder's weight .

/QUOTE]

Yod, so are you saying that something can't be MOIST with ether,acetone, or other organic solvents, when partially saturated? And these solvents dont evaporate quickly? And doesnt a quart of Acetone, etc., weigh about the same as a quart of water? By the weigh (pun), I never mentioned water. Thanks.

 

[Ol` Joe]

How much difference in weight did you find?

I can`t see more then a tenth or two grain max of weight change due to moisture in a rifle powder charge unless the powder is wet to start with. There just isn`t that much moisture in 50 grs of powder. (powder will also absorb moisture from the air as well as dry out) Most measures show that much variation in charge weight in my experiance to begin with, especially with extruded powders. I would suspect the measure got knocked, the powder lot is different, or some other source for the wgt change and reset the measure to drop the prefered charge.
Then again I`m anal and weight 90% of my rifle charges anyway.

 

[BIGJACK]

Be aware that a major component of sulfuric acid is water, and adding water only reduces the concentration.

 

[Fatelvis]

Joe, I dont remember exactly, but I believe the difference was around 1/2 grain. I was loading 24.1 grains of RL15 under a 77SMK, and the additional half grain would make it dangerous. I guess this is just another reason to keep your loads moderate!