Loaded rounds laying in sun

[Dave58]

I made the mistake of laying my loaded rounds on the bench in the sunlight while I was hanging targets.

I didn't let them cool and shot them through the chrony and got velicities all over the place.

After I realized how hot (temperature) they were I let the remainder cool down in the shade...velocities were good after that.

The powder is H4831sc in a 6.5x284 Laupa case.

I will not make that mistake again.

Is H4831sc a temperature sensative powder?

Thanks,
Dave

 

[barnesuser28]

no, it is one of hodgdons extreme powders. Extreme Rifle Powders

http://www.hodgdon.com/smokeless/extreme/index.php

 

[338winmag]

H4831sc is advertised as temp insensitive. I will admit I do drink some of the "kool-aid" regarding this claim but not really sure how valid it is. I use this powder in 3 rifles but mainly for the purpose of consistent FPS and very low ES.

Having said that, the claims are that it is tested up to a heat of around 101 degrees. Leaving those rounds out in the sun for even 15 minutes, I am willing to bet those cases are far hotter than that. I made the same mistake a while back and got some eradict velocities and groups. My cases were almost a bit hot to handle. I think you are all right and just remember to keep them in the shade.

 

[Lefty7mmstw]

I've shot the temp. stabilized h4895 from below freezing to a hot summer day( in my 25wssm), and the change is 100 fps or so, or exactly what you would expect with any other powder. The rifle, cartridge case, and primer aren't temp. stabilized, why would you expect the same speeds if any of those are subject to temp. extremes. I've seen similar with other h powders, but this one stuck in my head. I go for what shoots well in both high and low temp ranges and don't try to trick the system. I am lucky here in N.D., I can wait a few days and get both extremes.