Temperature sensitivity of US869

[meichele]

I am headed out tommarrow to do some load development. While I am there, I was going to chrony some loads with US869. It has been about -8 degrees here and thought that would be perfect to keep some loaded ammo out side over night and some in the house at 68 degrees, chrony them and note the differance. I will post agian tommarrow after this test. I will be testing this in a 300 RUM with 180 ACCUBONDS.

Has anybody tried this already and if so, what did you conclude?

[Buffalobob]

Not at those temperatures.

But the difference between 65F and 95F is pretty radical.

[CatShooter]

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"... I will post agian tommarrow after this test.

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Looking forwards to your results.

[jmden]

+1

[Hired Gun]

It's going to be big. I have watched Varget, IMR-7828, RL-25, RL-22, Retumbo, H1000, H-380, IMR-4350 IMR-4831 plus other so called temp stable powders all at one time or another started chronographing in the morning on through the mid day heat and you can watch the velocities go up as the heat increases. In my 100 round boxes I carry for my long range 300Wby I am thinking of loading up 10 each for each temp range to keep my velocity as close to 3100 fps as possible. I use a custom BDC dial on my scope and it is imperative I keep my velocity constant. Back in the olden days I didn't shoot over 400 yards much and 100 fps one way or another didn't ever make any difference while shooting game.

[41mag]

In one very limited test, we shot three loaded with 92 grs at 98 degrees F. then followed up with three of the same which had been put into a cooler and brought down to 60 degrees. The net finding was about 250 fps of velocity loss for the colder ones.

So far this has worked somewhat along with our drops and the Exbal we set up for our rifles.

I am definately interested in what your going to get on the lower temps.

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In one very limited test, we shot three loaded with 92 grs at 98 degrees F. then followed up with three of the same which had been put into a cooler and brought down to 60 degrees. The net finding was about 250 fps of velocity loss for the colder ones.

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A++ work/data. The approach is not perfect (at 60 deg the air in the pipe will be denser) - denser air would lower the velocity even more (but probably less than 3%). What a great idea - work up a velocity/temp data chart.