Quote:
Fast twist barrels, when used with heavier bullets, have shorter life, because the time in the barrel is longer, and the peak temperature curve is longer.
If you shoot light weight bullets, the barrel life is the same.
Not necessarily. I think that it depends a great deal on the capacity and velocity potential of the cartridge the barrel is chambered for. Speaking in terms of off the shelf stuff, I think you are generally correct. But with larger capacity cases and higher velocities found in many custom applications, I believe barrel life is often going to be significantly shorter in a fast twist regardless of bullet weight.
Using .224's as an example, I think you are probably right when talking about .223 class cartridges. But in my limited experience it has not held true for .22-250 class cartridges. Using a 55 gr. bullet at 3600 fps as an example - it will be spinning at about 185,000 RPM with a 14 twist barrel, 324,000 RPM in an 8 twist.
My experience has been that the extra 120,000 RPM makes a big difference in useable barrel life with even light weight varmint bullets such as the 55 Vmax. At over 300K RPM, it simply does not take much to compromise the integrity of a thin jacket. Going back to one of my own barrels mentioned earlier in this thread, an 8 twist .22-250AI, at 700 rounds the throat really didn't look all THAT bad. About like you'd expect for that number of rounds, really. But, bullets were inclined to go poof with monotonous regularity at that point. That includes 55 gr. Vmax. Again, my take on it, is that the centrifugal force of the extra 120,000+ RPM, as compared to a slower twist barrel, was enough to cause jacket failure where it would not have been occuring without the extra 120,000 RPM.
Nothing but my own opinion, but I really do think with fast twist barrels, that as case capacity and velocity go up, the rate at which barrel life decreases is accelerated - regardless of bullet weight. But for garden variety .223', I think you are correct and that what I'm saying is a totally moot point.
- DAA
Fast twist barrels, when used with heavier bullets, have shorter life, because the time in the barrel is longer, and the peak temperature curve is longer.
If you shoot light weight bullets, the barrel life is the same.
Not necessarily. I think that it depends a great deal on the capacity and velocity potential of the cartridge the barrel is chambered for. Speaking in terms of off the shelf stuff, I think you are generally correct. But with larger capacity cases and higher velocities found in many custom applications, I believe barrel life is often going to be significantly shorter in a fast twist regardless of bullet weight.
Using .224's as an example, I think you are probably right when talking about .223 class cartridges. But in my limited experience it has not held true for .22-250 class cartridges. Using a 55 gr. bullet at 3600 fps as an example - it will be spinning at about 185,000 RPM with a 14 twist barrel, 324,000 RPM in an 8 twist.
My experience has been that the extra 120,000 RPM makes a big difference in useable barrel life with even light weight varmint bullets such as the 55 Vmax. At over 300K RPM, it simply does not take much to compromise the integrity of a thin jacket. Going back to one of my own barrels mentioned earlier in this thread, an 8 twist .22-250AI, at 700 rounds the throat really didn't look all THAT bad. About like you'd expect for that number of rounds, really. But, bullets were inclined to go poof with monotonous regularity at that point. That includes 55 gr. Vmax. Again, my take on it, is that the centrifugal force of the extra 120,000+ RPM, as compared to a slower twist barrel, was enough to cause jacket failure where it would not have been occuring without the extra 120,000 RPM.
Nothing but my own opinion, but I really do think with fast twist barrels, that as case capacity and velocity go up, the rate at which barrel life decreases is accelerated - regardless of bullet weight. But for garden variety .223', I think you are correct and that what I'm saying is a totally moot point.
- DAA
