First groups with 6.5-284 LSR

[jb1000br]

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Why would humidity matter?: More humid = less dense air


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Being a br shooter, I am surprised that you have not heard of this before. Humidity changes everything from internal ballistics to external ballistics. When there is a humidity change, a lot of close range br shooters (myself included) will change powder charges to compensate or change powders entirely-going from say 8202 to 322 to change pressures back to their "sweet spot".
Externally, some guns that are on the ragged edge of stabilization in low humidity will not make it to the target or keyhole the target in high humidity. In my experience, humidity plays about as big of a role in this as air temp sometimes. /ubbthreads/images/graemlins/smile.gif

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Nevermind -- i'm a ******* -- misread, i had my wires crossed /ubbthreads/images/graemlins/crazy.gif

You higher elevation is probably close to cancelling out the humidity difference.

I still think you have a hot lot, cause i have talked to people in So Cal shooting a similar load to mine with no problems--desert and all.

My 6.5 hasnt seemed to care about humidity so i havent changed much -- just chasing the lands.

And when it gets HOT i just keep the ammo in the shade -- If the thermometer inside my ammobox reads 60-80deg I'm GTG.

JB

 

[goodgrouper]

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Nevermind -- i'm a ******* -- misread, i had my wires crossed

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No not at all!


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You higher elevation is probably close to cancelling out the humidity difference.


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Even though your higher humidity does cause bullets to travel through less dense air, it is a very small difference (less than an inch at 1k with 10% humidity vs 90%), on the other hand, elevation makes a ton of difference in trajectory. My .223 shoots like my old 220 swift when I'm at 10,000 feet!

I was just trying to say that it seems weird that bullet stabiliztion is harder to attain (it seems like) when the humidity is high, so there must be something about those water droplets in the air that makes a bullet fly higher impact but also seems to degrade it's ability to stabilize.
And then again, maybe I'm misreading the elements at the range. Anyone have an indoor, air conditioned 1k range we can borrow? /ubbthreads/images/graemlins/grin.gif

 

[Mikecr]

So whats the effect of humidity to BR shooters? The mechanics of it?
My software shows it as having such a tiny effect on Mach#, CD, Sg, and even drop, that it could be completely eliminated from consideration. Unless you load powder outdoors, I can't see it.

 

[Brent]

When the temerature drops it's ability to hold water is reduced thus the percent humidity goes up, something like it doubles for a 10 degree drop in temp I think it is. What you "may" be seeing is a drop in temp let's 'em go unstable?

I've never seen anyone do much of a test on the effects of humidity and never considered it at all myself it is so little in any ballistic program. The programs are either all wrong or what you're seeing is attributed to something else I guess.

Still, it's interesting, I never have heard of any BR shooters accounting for humidity.

 

[älg]

Goodgrouper, what I have read ( not experienced) is that an increase in humidity creates a higher apparent ballistic coeff. Maybe this would explain the higher elevation that br1000 talks about.