Humidity and reloading.
- Thread starter Jscb1b
- Start date
More humidity typically results in lower pressures and velocities. Popping primers in the rain is a different phenomenon.
There was a great recent thread on humidity and powder, will try and find it.
ETA:
www.snipershide.com
ETA:
How does humidity affect powder? A new experiment
The humidity of your powder can have an impact on your load's performance and consistency. But there's little in the way of actual public data about it. I wanted to collect the highest quality data I could, so I sent 120 rounds downrange to measure just that. I tested H4350 at five different...
www.snipershide.com
Nothing to worry about. I load in the garage and no problem even keeping powder in there in Houston.....plenty of humidity here.
If you are out in the rain shooting, it's easy to get a little moisture in the chamber and that can result in pressure spikes. (Really hard bolt lift and such). If you are near max charge for your rifle, then you have a good chance at seeing this happen. Happened to me a few weeks ago and I was shooting under a large cover. Water is very very hard to compress, so any moisture in the chamber effectively reduces your chambers volume size by whatever volume of water is in the chamber. I've never had it or heard of it causing enough pressure spike to blow anything up, but its something to be cautious of. Others here will know more about it I'm sure.
If you want your loads to be more consistent than this guy’s, don’t do what he does.
Control the humidity of your powder and where you use it. Powder humidity plays a measurable affect on velocity.
Zero issues with consistency. Single digit SDs and ESbin low teens. I store the bulk of my powder in the house and keep 1 lbs jugs on my bench...never leave it in the Autotrickler powder throw.
Properly stored in the original containers day to day variations in relative humidity and temperature have almost no effect on the moisture level of powder. When transferred to normal loading hoppers the ambient humidity has little effect on the overall moisture of the powder unless left for a time period longer than most people will take to reload.
This doesn’t mean that humidity doesn’t have any effect. Those who live in Arizona know this well. Over time the powder will reach an equilibrium that approaches the average moisture level of the environment.
Loss and gain of moisture is a mass transfer effect that requires time, temperature and concentration differences to occur.
This doesn’t mean that humidity doesn’t have any effect. Those who live in Arizona know this well. Over time the powder will reach an equilibrium that approaches the average moisture level of the environment.
Loss and gain of moisture is a mass transfer effect that requires time, temperature and concentration differences to occur.
Yes this is absolutely a thing and can vary speed pretty dramatic. Brian litz has his ammo in a humidity controlled cigar box if I'm not mistaken, and has talked about this being very critical.
The effects of humidity on powder have been established for decades. I don't know why that understanding comes and goes with time, but it seems to be forgotten and then comes up again every few years.
It doesn't mean the end of the world and is mostly the cause of some mystery to folks who don't know about it. Once in a while it surprises someone who was marginal when they ran a load development in an extreme of the wet end and didn't realize they were near a pressure limit, then their next batch goes higher when they load in dry conditions and causes a mystery.
The reason to keep track and manage your powder, is to attain batch to batch pressure/velocity. In games where you would consider it important to maintain an exact dope, you will want to study the concept and learn to track humidity. YMMV
Merry Christmas! Go JWST!
It doesn't mean the end of the world and is mostly the cause of some mystery to folks who don't know about it. Once in a while it surprises someone who was marginal when they ran a load development in an extreme of the wet end and didn't realize they were near a pressure limit, then their next batch goes higher when they load in dry conditions and causes a mystery.
The reason to keep track and manage your powder, is to attain batch to batch pressure/velocity. In games where you would consider it important to maintain an exact dope, you will want to study the concept and learn to track humidity. YMMV
Merry Christmas! Go JWST!
