From: sfaber@ihlpb.att.com
Subject: Re: Hot .308Win Load?
Organization: AT&T

From article <CA3s9s.B36@fc.hp.com>, by bartb@hpfcla.fc.hp.com (Bart Bobbitt):

# Ball powder tends to be more suseptable to high pressures when heated than
# extruded powder; one reason why it doesn't perform well in match rifles on
# hot days or when a round is chambered for longer than about 15 to 20 seconds
# before shooting it.

I noticed that for the fastest ball powder I used in some pressure tests
with .223 ammo, AA2230, gave quite dramatically higher pressures on a
hot summer day than on the 25 deg F winter day I did the same test.
The graph of peak pressure vs velocity seemed to stay the same, but
the charge difference to get the same pressure  amounted to about 1 grain.

Steve

From: gale mcmillan <gale@mcmfamily.com>
Newsgroups: rec.guns
Subject: Re: Ammo and heat
Date: 4 Jun 1997 13:00:50 -0400

Dragon wrote:

# Hey guys,
#         This may be a stupid question, but does anybody worry about
# keeping a loaded gun in their car on a hot Georgia summer day when the
# dashboard can get so hot, it can leave a blister?  If you keep a live
# round in the camber of a DA gun, what if it goes off?  Anybody know how
# hot ammo has to get in order to go off?

The danger is not that it will go off due to heat.  The problem is
should you shoot it after it has been at elevated temp.  Pressures go
sky high. Here in Phoenix where the temp will get above 115 degrees
loads that work fine when cool will blow primers when left in the car
just a few minutes