Cold (9*F) chamber and warm (60*F) ammo?

[Frostbite Slim]

Sunday I was shooting and had some flat primer issues. The load was .308 168 grain Berger Hunting VLD, 42 grains of Varget, once-fired FGMM brass trimmed at 2.005", CCI 200 primers. The rifle sat on the firing line for about an hour, while the ammo was in the truck. The first five shots had flattened primers. Weather was 9*F, baro was 28.47, altitude was 305 ASL. These same rounds were great in 26*F weather with similar pressure on the same range.

 

[treebasher]

Re: Cold (9*F) chamber and warm (60*F) ammo?

Here is a good write up on what you experienced:

http://www.shootingsoftware.com/ftp/Pressure%20Factors.pdf

 

[Frostbite Slim]

Re: Cold (9*F) chamber and warm (60*F) ammo?

Thanks! I will have to read that a couple of times to make sure that I understand it. VERY informative!

 

[varmint slayer]

Re: Cold (9*F) chamber and warm (60*F) ammo?

Good read treebasher. Thanks for sharing.

 

[CUTRIGHT]

Re: Cold (9*F) chamber and warm (60*F) ammo?

I couldn't get that link to load, what's the story?

 

[treebasher]

Re: Cold (9*F) chamber and warm (60*F) ammo?

Try this link:

http://www.shootingsoftware.com/tech.htm

Then scroll down to the article named "Pressure Factors: How Temperature, Powder and Primer Affect Pressure"

Or you can right click on the article link and select "Save Link As".

 

[CUTRIGHT]

Re: Cold (9*F) chamber and warm (60*F) ammo?

I had some 6.5-284 Shehane ammo loaded a little hot at the 1000yd IBS nationals up in Iowa back in 2005. I set my ammo in my cooler for the night and went to the line the next day thinking they would slow down at least a little bit, I blew primers.
I read a chart from Hodgdon one time that showed H4831sc gaining velocity in cold weather and thought it was a typo, I'm not so sure it was. I wish I could find that copy now that your topic has me thinking about it again.