barrel heating vs barrel life

[mosin46]

i know barrel heat is usually the enemy of barrel life. but is there any data showing where to stop and let cool or cool it down that addresses this issue. i know the variables: barrel weight,fluting,velocities used,leade constriction,load pressure,caliber-220 swift will heat way faster than 45-70. just wondering if there is any real data on what temp to stop all other factors considered. or,is it just a matter of experience and guesswork?

 

[NBPRP]

There probably is some empirical data out there regarding your question and one could research this matter in infinitum much like a dog chasing it's tail.

So be that as it may unless you are belt feeding to infinity your M1917 Browning .30 cal. machine gun, that has run out of water, you can shoot to your hearts content so long as you can touch you barrel and say one Mississippi, two Mississippi, three Mississippi. If you are not in significant pain after doing so you should be good for go to keep on shooting.

Case in point had a Remington 40-XC in 7.62 NATO on its second barrel that was a SS Obermeyer 5R which was 24.35" long with MTU taper and twist in 11". At the Minnesota State Championship in Duluth, MN. the team match was held on July 4th with the individual match held the following day or July 5th. As luck would have it that entire summer was warmer than normal and that was the 12th match of that summer. At the end of each rapid fire stage, 200 yards sitting and 300 yards prone, when moving off the firing line you could touch your barrel but certainly not grab it to carry by the barrel due to it being too hot.

The entire weekend was in the mid-high 80's and the pitch count at the start of the team match was 4,264 rounds through the barrel. At the start of the 600 yard slow fire prone stage of the match the barrel had 4,290 rounds through it. At the end of the 600 yard stage the barrel had 4,312 rounds through it and I had fired a 200 -10X clean. The load was LC 77 Match case, Federal 210 Match primer, 46 grains of IMR 4831 behind a 200 grain Sierra HPBT Match King seated to 2.800".

At the beginning of the next season, in the spring the barrel had 5,415 rounds through it and was replace with a fluted Obermeyer that was in my stable that I was itching to try. I did not notice a big drop in accuracy but decided to change the barrel to be safe as it was near the start of the season. I did not want to chance the barrel going out just before Camp Perry and then be faced with scrambling around to get the barrel swapped out.

 

[Robert4]

I'd say it's experience and guesswork. If you could quantify the variables for any specific case, you would find the barrel heat vs erosion to be a sliding scale. Consider that as a barrel warms, the rate of heat transfer from the critical throat area slows. Heat transfer rate is driven by the difference in temperature between the barrel material and the surfaces in the throat. A warming barrel sets up a positive feedback loop of further heating the throat.