Humidity and load developement

Seabeeken

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Apr 30, 2013
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509
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West NC
Anyone test the effects of humidity changes in the reloading room while doing load development? Just watched a video on YouTube about how high and low humidity levels effect load development.
There is an excellent writeup in the Norma reloading manual on this very subject and surprising results. Brian Litz also wrote about it.
 

Bob Wright

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Jan 23, 2018
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Litchfield Park, Az.
In the video I watched. The guy showed velocities between rounds loaded at 90%, 38%, and 10% humidity. There was a 200 fps difference between the 10% and 90%. With the higher velocity going to the 10%. Makes me rethink my load development, and wonder just how many times I was chasing my tail due to humidity.
Very significant. Concerning for safety alone.
 

Rusty PW

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Sep 27, 2016
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Brownsville Pa.
I seen that same video on youtube. I installed a Golden Rod in my powder cabinet to control the humidity. I did a little experiment. I put 20gr of RL26 in a pan on my balance beam scale. Left that on my bench for a week. Every day I looked at it. I could see the difference in weight change. It wasn't much, but you still could see it.
 

Barrelnut

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Dec 16, 2013
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End of the Oregon Trail
This is what I use. Got on Amazon. Keeps track of H/L temps and humidity. The gun safe is in the reloading room. So I just keep this one above the bench. It has a magnet on the back to attach to anything metal. I also keep one in the camper....

1636852936370.png
 

Jeff Heeg osoh

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Sep 12, 2019
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132
Location
Wisconsin
I don’t think the humidity in your reloading room is a issue while reloading unless it takes forever and you leave stuff sit around unsealed.

The humidity becomes a concern on long term exposure after the seal has been broken on the jug. The thing that’s a concern is having a load that shoots lights out and then you a have a few months in the off season that the powder within the jug can either absorb moisture or dry down some do to the conditions within the room it was stored. Now your rifle is shooting like crap compared to when you put it away and what the heck happeNed.

I don’t worry so much on the small stuff - my 260 and H4350. But on my 416 with the 20N29 I do monitor the powder humidity in the jug I have a Kestrel drop in the powder all the time that tells me all is good and I’m floating at 58% humidity that is Blue toothed to the phone and if needed I can add a 59% Humidor pack that will maintain it.
The most appreciated part of this is maintaining a burn rate and quality that keeps load consistent jug after jug and season to season, such a simple thing that has saved money, wear and time messing around having to keep doing load testing to stay in the zone. 58-59% is the sweet spot with 192.5 grains

The 416 is used pushing the 550s out 3000 + yards at events

osoh
 

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degreen

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Feb 24, 2015
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Lander, Wy
The main thing this video shows is. If you are doing a Saterlee test one day, and a week later you decide to confirm your data and load up some new test rounds. The humidity difference between these two load sessions could throw your data way off.
 

Bob Wright

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Jan 23, 2018
Messages
1,847
Location
Litchfield Park, Az.
The main thing this video shows is. If you are doing a Saterlee test one day, and a week later you decide to confirm your data and load up some new test rounds. The humidity difference between these two load sessions could throw your data way off.
I was looking at a load pressing close to max pressure by a grain or so under, then you start blowing primers unexpectedly. I live in a dry climate mostly and found this interesting as to pressure surprises with the exact grain charge. It's hard to assign one cause of velocity problems if this "little nugget" of info isn't at least considered during the year. Knowledge is good.
 

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