how long can powder be left exposed to the open air before it begins to deteriorate and lose its umph? Does ball powder deteriorate faster than extruded powder? Can you leave a powder measurer full of powder for a couple of weeks and still have it be potent. All of these questions were put to me and I had no answer, so, I am coming to the experts. Thanks for your help ... Tom Purdom

In open air, the solvents in gunpowder will evaporate, which will do it no good. The other things to be concerned about would be direct sunlight, high temperature and humidity accumulation in exposed powder.

The question is, how long can powder be kept in a powder measurer before it will become less potent, one day, two days, one week, a month? Any ideas? Thank you. Tom Purdom

In a powder measure with a lid, in a 70 degree room that is not humid and no direct sunlight, probably a month or more. The higher above 50% the humidity goes and the warmer and more sunlight the powder is exposed to, the shorter it's life. If the powder measure is left in an open container, the solvents would evaporate and moistue would enter, probably changing it's burning rate. The best answer probably can be had by calling Hodgdon Powder Company. Very friendly people. If anyone would know, they would.

quote:

Originally posted by 7x57mm:
The question is, how long can powder be kept in a powder measurer before it will become less potent, one day, two days, one week, a month? Any ideas? Thank you. Tom Purdom

Years, unless it is in direct sunlight. Even in sunlight, I would not worry about a month.

Take a read of the smokeless article in Wikepedia http://en.wikipedia.org/wiki/Smokeless_powder. This article does not go into depth on the deterioration of gunpowder but it does describe the constituents. If you understand what gunpowder is mostly made of, nitrocellulose and nitroglycerin, mixed in a binder, well these are polymer chemicals. Probably thermoset polymer chemicals. We have lots of polymer chemicals in out life, think of any rubber, plastic, paint, etc. And what damages this stuff, well top on the list is sunlight and heat. I don’t think the evaporation of the solvent does much, but I don’t think it is a good thing either. Basically if you started with good fresh powder, and your powder measure is in the typical dark cave where reloading troglodytes live, I don’t think a month of exposure is going to do much to the powder. If however you park your powder measure right next to your Florida boat dock, and leave it in the sunlight and salt air, well maybe nothing is going to happen to anything plastic in the first month, everything metal will be rusted, but within four months you will see plastic deterioration.

You really don’t want to thermally cycle your powder, the resin that holds everything together, nitro compounds etc, will break down. It takes time, and I have no idea of how many cycles. I know this sort of thing has been tested, especially for rocket motor propellants, but I don’t know where to find the data. Rocket motor propellants are smokeless powders, made up of the same stuff but in different proportions, because they want a different burn rate.

Fella's, thank you one and all for your comments. My questions have been answered. I hope this response finds you having a great day. Tom Purdom

Back up as second here!

Let's talk about "house keeping."

When you're done loading, you should return the powder to the container it came in. The container is designed to store the powder, also if the house catches fire, the container is designed to "burn" rather than become a "bomb."

Unless I'm in the middle of a "run" for one caliber, I put the dies back in the box. Store them away. Put the powder scale back in its box.

Put notes/labels on the ammo I just loaded and put it away.

I saw a photo of somebody's "loading setup" -- a crowded coffee table in the living room, covered with magazines and empty beer bottles, pizza containers.

You're potentially building a small "bomb" -- at the very least an "explosive device." Lead and powder are toxic. Powder can be degraded.

Also, if you leave powder in the measure, there's every chance you can mix two different types together. Keep them in their containers.

One last rant --

READ the label on the powder and bullets 3 times! --

Read the label, take it off the shelf. I put my finger on the powder type just to make the reading "physical."

Read the label before you pour it in the powder measure.

Read it a third time when you replace the cap and set it on the bench. Keep the container on the bench (ONE container, the one being used!) While you're loading.

Doesn't hurt to double check the scale settings and re-read the label on the powder.

Over-kill yeah . . . Drummed into me working in a pharmacy in the Army. You don't want to get lax about that container of powder, the weight of the bullet, settings on the scale.

What 45/70 said.

You hear it all the time about someone blowing up a firearm because the started loading using the powder in the measure thinking it was something else. Better safe than sorry. Put it away and start fresh each time. Just takes a minute.

Every now and then I'll leave a small amount of powder in the measure and not get back to it for weeks (or longer). If it is truly a small amount, I'll just dump it. If it is a significant amount, I'll save it and have never had any problems (provided there is no question about its identification.)

I normally NEVER remove the powder from my shotshell loading bottle between sessions; however the loader is stored in a dark closet when not in use and I typically only use one powder with a given gauge (and label the powder container, anyway) so powder identification is no problem. It might be ten months between loading sessions and I have never noted any difference in the performance of powder stored this way and "fresh" powder from the cannister.