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Today I was going to load up a bunch of my new hunting loads but decided not to because the humidity is higher than normal (snowing good here). Normally we are around 30% and today really high at 55%-60%. Could this affect my loads?, I imagine that I am just parranoid.

Thanks all.
 

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Prolly not.

Certainly that minor change in humidity is not going to make a difference you can see in factory guns.
 

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Here in the steamy south, never had a problem with it. And I haven't heard any of my shooting buddies complain about it either.
Just don't reload outside in the rain.
 

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I saw an intersting article some time ago regarding the making of Olympic quality ammunition by the company Eley, I think it was. They identified all the variables they could which might affect their product. One of the things they discovered which made a measurable difference was the weather outside the plant where the powder was produced on the day it was produced. They actually found that they needed to factor it into their loading process to get the results they wanted. I suspect most of us have neither the level of skill nor the isolation of our variables down to where the weather will matter much, if at all, when it comes to building ammo. It is interesting to know, I think, that it is influential though.
 

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Not very scientific, but when I was loading up a large batch of .308 Win. ammo over a period of several days, the first day was hot and dry and the powder charge was 49.0 grains. It rained late that night and into the next day. When I continued the reloading with the powder which had been in the measure over night, the charge thrown was 49.2 grains. I believe all smokeless powders are hygroscopic to some degree, even the double based type. How much it will affect your loads is something I cannot answer.
I have also run into this when loading handgun ammo with certain pistol powders, especially Unique, although it never seemed to affect performance as far as I could tell.
About the only way to get away from this problem is do your loading in a perfectly climate controlled enviornment, probably something way beyond the means of most of us. :roll:
Paul B.
 

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I live on the NC coast, and for about 8-10 months a year, the humidity stays at or above 80% continuously. Often up at 100% for a day or so (foggy, muggy, and rainy in summer). It is not unusual for me to load with an 85% humidity, although I usually try not to load in a storm (low pressure, higher humidity, and I bet it would make little difference at my level of perfection). I have a buddy, who competes in a type of 1000 yd benchrest, and we have talked about loading up ammo in the middle of a hurricane to have ammo loaded with a LOW internal case pressure. We have theorized (over a few too many beers) that Hornady's Light Mag ammo may use lower than normal, even partial vaccum loading conditions. (I wouldn't bet the farm on it though). We never have conducted a test on this low pressure theory, (falling limbs, rising tides and alarmed wives don't make for good loading conditions :shock: ) but high humidity hasn't cost me any venison, and I have shot some fine groups loaded in our hot, humid summer weather. Just my thoughts, humbly. :)
 

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A local benchrest shooter who is a retired, professional laboratory technician talked about this recently. When he still had access to labs at the University of Wyoming he tested for humidity, temperature, and barometric pressure under controlled conditions. He was most interested in the temperature change and how it affected his powder measure.

He found no significant difference caused by any of these factors. This is a trained researcher using a facility which allowed him to control for climate: no measurable difference.

He can explain plenty of other variables that will affect loads such as length of drop tube, physical inconsistencies in operation of powder measure, etc. Having seen his rifles, his loading equipment and technique, and the size of his PRACTICE groups, I am convinced that he detects differences that 99+% of all reloaders could not.

At least I am convinced I will never be precise enough in my own approach to loading to ever see differences caused by humidity, temperature, etc. Heck, I'm a + or - 0.20 grains kind of guy, at best. :wink:
 
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