Humidity?

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Humidity?

Postby mr surveyor » 23 Sep 2018 21

How much effect will humidity actually have on group sizes on paper?

It could be my current "new normal" abilities, but I don't think so. I had my normal limited range time between 6:00 and 7:00 pm today and had time to barely squeeze in five targets of 5 rounds each to try some .44 mag loads. I figured they would stay in the 1.5" group size, at 100 yards, for the most part while I moved the cross hairs for a better POA/POI. Nope .... all five groups were 2" up to 4" and just nasty looking.

Temp was a nice 80°, wind was very calm, been raining for a few days but none falling, mostly cloudy .... but the humidity was 90%. Actually, the humidity was such that I did have to wipe off the shooting glasses every shot, but I never sent a round down range if I couldn't clearly see the target.

I'm just wondering if anyone else has noticed any correlation between humidity and target groups?


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Re: Humidity?

Postby Ranch Dog » 24 Sep 2018 06

Humidity plays into shot performance, but would not be noticeable at the ranges we shoot our 92s. It is part of the consideration of distance shooting along with temperature, barometric pressure, and altitude.

Specifically, total air saturation, 100% humidity which means visible moisture in the air, will reduce a bullet's velocity 1.5%. That's it, from totally dry air, no humidity. Most of our shooting in eastern Texas is probably done near 70% humidity or better so the change we would observe is quite a bit less than the 1.5%. Most ballistic software does not even bother with a humidity correction because it is so small. You really need to be reaching out for it to matter.
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Re: Humidity?

Postby mr surveyor » 24 Sep 2018 08

Thanks. I guess I was just having a "not so good" day.


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Re: Humidity?

Postby Ranch Dog » 24 Sep 2018 12

It is weird how one day can be so good and the next, well, not so good.
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Re: Humidity?

Postby Ohio3Wheels » 24 Sep 2018 14

Only problem I have with higher humidity is with the BP cartridge guns that need to have the barrel wiped more often.

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