barrels

[Moose420]

what causes a barrel to "burn out" and become inaccurate? Is it velocity or something else. Where is the safe zone?

 

[2506]

It is the hot powder gas that gets the throat. Every time you fire a rifle it is like hitting the throat with a blow torch for a moment.

 

[Bob3700]

The combination of hot gasses and burned abrasive materials causes the throat to get rough and wear. The wear changes the dimensions of the lands, the rough tears the bullet jackets.

Bob

 

[Obtunded]

The area of the barrel that is affected is the throat area just ahead of the chamber. Heat that is generated by burning powder and,to a greater extent) the pressure, does to barrel steel what it does to all steel: Make it succeptible to wear and erosion. Furthermore, the steel will show signs of cracking or "heat checking" in the throat area when exposed to high heat/pressure.

http://accurateshooter.wordpress.com/2008/01/02/barrel-throst-erosion-revealed/

The best defence against it is to use loads that aren't excessively "hot", allow proper cool-down between shots and avoid overly agressive barrel cleaning methods. Anecdotal evidence supports the use of Moly coating or boron nitride as a means of reducing some of the wear, but this is a controversial topic.