Reloading question

[66GTO]

My question is: Does humidity while reloading have any effect on the reloads?

I was going to reload a couple of hundred rounds of .357 but it started raining before daybreak. I reload in my garage and decided to wait until this cold front clears out the humidity. I am probably being overly cautious because the typical summer day here in Florida is more humid than a rainy winter day.

[Hobie]

Not if you do them all the same and keep the ammo out of the rain... Honestly, I don't pay attention to that. The way I load all the cartridge case prep is done prior to actual loading. Then the charge is weighed poured and bullet seated before moving on to the next powder charge. The powder is minimally exposed to humidity such that it could "soak up" water from the air or dry out in dry air. I think it is a non issue. More important is if you are storing your powder in a room with large temperature swings.

[RKrodle]

I also load in my garage, I hope some day to have a dedicated area. I've never seen a problem caused by humidity that I'm aware of. Powder is some amazing stuff, keeps just about forever and really doesn't seem to be affected by much. With that said, you should still take care with powder and primer storage.

[66GTO]

Thanks to both of you for relieving my concerns.

I don't store my powder or primers in the garage, I keep them inside where the A/C runs about 10 months of the year. I keep my dies inside also so they won't rust from the Florida humidity.

[Mike Rintoul]

Powder is manufactured under a tightly controlled moisture free environment and includes processes to remove moisture from the powder. It is sometime coated with a solution to help deter moisture absorbancy - although the coating is never 100%.

Powder is like beef jerky. Once you open the bag it will continue to get heavier as it absorbs moisture.

Each powder has a maximum absorbancy that is the point where it won't take in any more moisture. Powder doesn't shed moisture, so once it takes it in it essentially stays there.

A given amount of fresh powder will weigh a certain amount. Months or years later the same volumetric amount can weigh more if it was allowed to take on moisture and especially if it reached its maximum absorbancy.

Usually there is not enough moisture to effect the performance of the cartridge when loaded. On a mico level the load is slightly different and will therefore have different characteristics, like burn rate and combustion, but not really enough to measure the difference unless you are dealing with a cartridge with a lot of powder like a 500NE.

Our powder room is temperature regulated to stay between 70 degrees and 75 degrees. There are dehumidifiers running constantly to keep the humidity as less than 40%. We also use calcium chloride pellets near all the powder canisters.

For the home handloader this should not be a major concern but it is something to consider if you will keep canned powder around for a long time or if you are loading for the utmost precision.

[66GTO]

Thanks Mike. Nothing like advice from an expert.