Cooling down the bore.

[BoydAllen]

IMO the whole thermal shock issue (as it would apply to the cooling of a reasonably hot rifle barrel) is an unproven theory. Heat moves based on conductivity of materials and difference of temperature. If it is very hot outside, the difference in temperature between the air and a warm barrel is relatively small. If you have gotten your barrel too hot to touch you have already crossed the line (for an accurate rifle), and while you may find it convenient to cool it down quickly,IMO the damage has been done. This is one option that I have never seen any test results on. http://www.lothar-walther.com/396.php

 

[M14AMU]

Shoot sloooowwwwweeerrr!

 

[Grimstod]

Did some testing with the new 6mm BRX. I think running the fan also helps settle the barrel a little and cold bore shots are not radically off as far as they would be without this.
Here you can see temperatures after a 5 shot string and then after 30 sec of fan run time.
Ambient temperatures of the metal were 79f.

 

[BenPerfected]

If you start shooting with the barrel at 80-90 F, at what temp do you see the groups start to open?
Ben

 

[Grimstod]

When it is to hot to touch.