Accuracy "stability" with temperature change-and lot testing

E

eeleater

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With a given gun- will the accuracy of a lot of ammunition vary with temperature, if the temperature stays above , say 50 degrees F.
To be more specific- with Eley Tenex EPS or Match EPS.

I am involved with Silhouette shooting- and enjoy shooting my silhouette guns off the bench. I have found when it is around the freezing mark I see a clear drop in the POI in the first shot (or two) from a cold barrel- and they cool off fast if you are shooting at the relativly slow rate found in a match. My impression is that some lots do not seem to shoot as well when it is very cold- vs. how they do in warmer weather. Could be me shiverrrrringggg also...

I am planning to do lot testing before buying a quantity of ammunition- which will later be shot in much warmer temeratures than we are currently having. With the prices of ammunition rising, this could be an expensive mistake if the lots which shoot well at 50 to 60 degrees are noticably worse at 90 to 100 degrees.

Please let me know your thoughts and observations.
 
eeleater said:
I am planning to do lot testing before buying a quantity of ammunition- which will later be shot in much warmer temeratures than we are currently having. With the prices of ammunition rising, this could be an expensive mistake if the lots which shoot well at 50 to 60 degrees are noticably worse at 90 to 100 degrees.
Click to expand...

eeleater,

DO NOT DO THAT!!!

 As I have said many times before on this board; any caliber bullet gains or looses velocity at an approximate rate of 1 f/s per degree change in temperature.

That being said; if you test ammunition in temps of between ±50° to 60° and find the perfect lot, then shoot that same lot after the weather has warmed up to 90° to 100°, it may turn out not to be what you thought it was due to a difference in velocity of as much as 50 f/s!

I have know of several shooters who have tested, then gone out and bought case lots of ammunition during the dead of winter when things are at or below freezing knowing this was the perfect answer to their quest only to realize later on, once summer's heat and humidity had arrived, that the lot wasn't quite as good as they had thought it was.

If you can, do yourself a favor and wait until the weather has had a chance to warm up to closer to where you will be shooting at before doing much testing. You will be much happier with the results.
 
temp change same lot

Over the last month i have tested a lot just what you askew I found that even small temp changes can have a large effect you have to find lots for div. conditions (temp) I attaché a scan same ammo / gun combination one week apart, one shoot at +1 C, one shoot at +18 C
:eek:
 

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Don, can you put that in F°, never could figure out c°? With all this muzzle device (tuner) business going on both of these boards, I thought I read somewhere that once you have your muzzle stopped, it don't matter about ambient conditions. kinda hard to keep it all straight, thanks, Douglas
 
it not as much the muzzle as it is the bullet is my belief. i could be wrong. i test my lots inside at 75 degrees myself. i'll be shooting in warmer temps also so i just buy a few bricks of that ammo until i can get into higher temps and test again. then i'll make my move for another warm weather round. what shoots well now might or might not shoot well later in warmer/colder temps. i've seen it happen in centerfire guns as well.
 
Air temperature and density

If you go to the ARG Web-Site, go to the News section, scroll down 2 or 3 articles and there is an article on Air Temperature and Density, how to graft it out on a chart and with that how to chose the correct speed ammo for the match. www.22arg.com As the match warms up during the day, you may have to change ammo to match the conditions. Andre'
 
Douglas +1C = 33,8 F +18 C =64,4 F
I spend a fair amount of $$ and was under the impression I got it right until we had a large temp change. I had a few lots of Eley ESP tested for small group in my gun once I got to the range I could hear the inconsistency during fire ring and the groups opened up in some of the lots other stayed small
The weather changed a week later and gets warmer the same thing reversed the ammo which shoot small opened up and the inconsistent from the week before closed up.
I believe also the ignition & powder plays a roll in cold weather condition.
 
When I am shooting my benchrest 52 I find that the higher velocity works in the colder weather (1060 or so in about 10F) but won't shoot at all in the warmer temperatures. Slower ammo seemed to work better for me in the summer time :)
 
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