Barrel life

[RHux]

I am thinking about using my 270WSM with H1000 at 57,000.
Do you think I will realize the same barrel life as the 6.5 GAP is reported to have ?

 

[JBT47]

I am thinking about using my 270WSM with H1000 at 57,000.
Do you think I will realize the same barrel life as the 6.5 GAP is reported to have ?

Should be similar...the 6.5 SAUM does not have anything magical about it to achieve good barrel life if using a cool burning powder at lower pressures.

 

[Bart B.]

A good way to calculate barrel life is to first calculate the cross section area of the bullet (or area of circle at bore or groove diameter) in square millimeters. The number is very close to the max load charge weight of powder that will get about 3000 rounds of match grade barrel and bullet life. About 6000 rounds of big game factory hunting rifle barrel and hunting bullet life. It changes a little across powder burn heat index.

Increase the charge 40% and barrel lives are cut in half. Double it to a 100% increase and barrel lives are one fourth as much; 750 rounds do match grade barrels and 1500 for big game ones.

Data based on Sierra Bullets' test barrels starting out as 1/4 MOA average then opening up to 3/8 MOA average for match bullets, over twice that for hunting bullets. Top ranked competitor's barrel lives were also considered.

 

[dcali]

A good way to calculate barrel life is to first calculate the cross section area of the bullet in square millimeters. The number is very close to the max load charge weight of powder that will get about 3000 rounds of match grade barrel and bullet life. About 6000 rounds of big game factory hunting rifle barrel and hunting bullet life. It changes a little across powder burn heat index.

Increase the charge 40% and barrel lives are cut in half. Double it to a 100% increase and barrel lives are one fourth as much; 750 rounds do match grade barrels and 1500 for big game ones.

Data based on Sierra Bullets' test barrels starting out as 1/4 MOA average then opening up to 3/8 MOA average for match bullets, over twice that for hunting bullets. Top ranked competitor's barrel lives were also considered.

Interesting. Is there more detailed information on this published anywhere? My first instinct would be to use the bore's circumference as a base dimension to work off of.

 

[Bart B.]

To me, bore capacity is fixed for a given bore diameter The more burning power pushed through a given caliber, the more wear there will be. Then I got to thinking on all that stuff. Somehow, a standard has to be established for bores.

As far as I know, I'm the first one to develop the formula and publish how its used. That was back in the 1980's when I queried Sierra Bullets on their machine rested test barrel lives that were not influenced by humans when fired. Then got barrel lives from match winners, record setters and National champions because they hold rifles most repeatable from shot to shot. Did a "best fit curve" on the data points then found a formula that calculated it. Here's my spreadsheet for it:



This shows trends, not exact data. Best used as a rule of thumb, perhaps a fat thumb at that. Depending on what you use to calculate bore cross section area, answers will have a small spread. Bore or groove diameter, or even SAAMI's bore area spec listed in their centerfire rifle document, will have a small percent spread in bore cross sectional area. Yes, it's an empirical approach; better than none at all.

Forum member mikecr used my formula along with Quickload's powder heat indices and a different barrel wear standard to make his version. It gives about 10 to 20 percent longer barrel lives. Its best part is using heat indexes. Hotter powders erode barrels faster. Here's its info:

http://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/

 

[TAJ45]

To me, bore capacity is fixed for a given bore diameter The more burning power pushed through a given caliber, the more wear there will be. Then I got to thinking on all that stuff. Somehow, a standard has to be established for bores.

As far as I know, I'm the first one to develop the formula and publish how its used. That was back in the 1980's when I queried Sierra Bullets on their machine rested test barrel lives that were not influenced by humans when fired. Then got barrel lives from match winners, record setters and National champions because they hold rifles most repeatable from shot to shot. Did a "best fit curve" on the data points then found a formula that calculated it. Here's my spreadsheet for it:

View attachment 1033375

This shows trends, not exact data. Best used as a rule of thumb, perhaps a fat thumb at that. Depending on what you use to calculate bore cross section area, answers will have a small spread. Bore or groove diameter, or even SAAMI's bore area spec listed in their centerfire rifle document, will have a small percent spread in bore cross sectional area. Yes, it's an empirical approach; better than none at all.

Forum member mikecr used my formula along with Quickload's powder heat indices and a different barrel wear standard to make his version. It gives about 10 to 20 percent longer barrel lives. Its best part is using heat indexes. Hotter powders erode barrels faster. Here's its info:

http://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/

Excellent presentation of your reasoning, methods and including similar efforts with credit.
That type of approach is commendable.

 

[mikegaiz]

To me, bore capacity is fixed for a given bore diameter The more burning power pushed through a given caliber, the more wear there will be. Then I got to thinking on all that stuff. Somehow, a standard has to be established for bores.

As far as I know, I'm the first one to develop the formula and publish how its used. That was back in the 1980's when I queried Sierra Bullets on their machine rested test barrel lives that were not influenced by humans when fired. Then got barrel lives from match winners, record setters and National champions because they hold rifles most repeatable from shot to shot. Did a "best fit curve" on the data points then found a formula that calculated it. Here's my spreadsheet for it:

View attachment 1033375

This shows trends, not exact data. Best used as a rule of thumb, perhaps a fat thumb at that. Depending on what you use to calculate bore cross section area, answers will have a small spread. Bore or groove diameter, or even SAAMI's bore area spec listed in their centerfire rifle document, will have a small percent spread in bore cross sectional area. Yes, it's an empirical approach; better than none at all.

Forum member mikecr used my formula along with Quickload's powder heat indices and a different barrel wear standard to make his version. It gives about 10 to 20 percent longer barrel lives. Its best part is using heat indexes. Hotter powders erode barrels faster. Here's its info:

http://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/

In my 60+ years of shooting experience, I think the spreadsheet Bart shows in his comments is extremely accurate. I have shot out over a dozen barrels and the numbers are right on.