Ammunition Temp. at Range

[slim56]

I am curious, how important is it to control ammo temp. at range to achieve best possible accuracy? What do shooters use to keep ammo at consistent temp at range? How important is temp at the time the loads are made at the bench? I know that this is a lot of questions on a single subject, but I shoot in southern NV and air temp. can change 40 degrees from beginning to end of shoot, not to mention effect of direct sunlight on ammo.

Thanks for the information.

 

[BoydAllen]

Although there is a lot that could be done in this area, my impression is that it is not being looked at by very many people. The main thing that I would suggest is to not let ammo sit out in direct sunlight on hot days.

 

[Viperdoc]

I have the same concerns: last year I worked up some great loads for pd shooting, but in the field, they were blowing primers.

Generally, the rate of a chemical reaction doubles for every ten degrees C, but is there a known relationship between powder charge and ambient temperature?

How can we work up loads at one temp and then figure out how they'll do at another temperature (without resorting to warming or cooling the ammo?)

 

[Cort]

I shoot with a fellow who keeps his ammunition in a small ice chest. I think he uses the ice chest as his ammunition locker at home and transports the cooler to and from the range. I don't know if he puts any cool packs in the ice chest on hot days.

Cort

 

[DOGCAPPER]

you are looking at density altitude...Temp is one of the high value varables in the calculation..

 

[riverwolf1]

In the early 80's I shot a .280 Remington at the Sihouette Nationals in Phoenix,all of my load development was done in San Diego! When the Navy team got to the Nationals It was hot as he!!, my rifle bolt had to be beat open with a hammer and we determined that if I put my rounds in a cooler with some ice to cool them down I wouldn't have this problem. So we cooled down the rounds and I would pull my ammo out just before going to the line and everything worked fine for the remainder of the match. So yes heat does impact loaded rounds. I lived in Las Vegas for 16 years and shot Hunter BR and short range BR at Desert Sportsman and yes I loaded at the range and did have to change powder loads as the day progressed.

 

[CaptainMal]

Last Monday I was testing a single load in 7MM Rem Mag with a new barrel on a Model 70 action I had. In the morning I chronographed maybe 15 loads over an hour, as I changed the BOSS setting on that barrel.

Stopped to cool the barrel and used another gun. Ammo was in a box in the shade but it is Summer in Florida. Couple hours late I continued with the gun and the velocity was up around 40fps. At the time I figured it was because of ammo temperatures.

It IS a factor.

 

[CPorter]

I've shot in matches that started in the 60s in the morning and was over 100 shortly after noon. I've tried using a pad that was moist for evaporative cooling and it helped. Best though to keep the temperature consistent in a cooler and then out of the sun on the bench. I may make a holder with a fan and moisture pad for the bench but it would be more of a novelty item.

 

[BoydAllen]

Trust me; this isn't about density altitude. But while I am on the subject, I don't know of a single short range benchrest shooter that claims that he can either load or set a tuner, by simply taking a DA reading and consulting a chart. Even the very best, show up a day or two before a match, and find their tune by trial and error, especially if they don't have any notes from previous experiences at that particular range.

 

[WyleWD]

Although there is a lot that could be done in this area, my impression is that it is not being looked at by very many people. The main thing that I would suggest is to not let ammo sit out in direct sunlight on hot days.

Agree with Boyd. We take our ammo to the matches in an insulted cooler and keep it there till our relay is called. We do NOT put a cool pad or anything like that in there. Just use the cooler to try to keep the ammo from being exposed to the sun / shade etc. IE keep the rounds consistent as possible temperature wise, but not too far under ambient temperature at the bench. And, oh yes, keep a towel or something handy to shelter them from the direct sun if that may or may not be shining on your bench. WD