Barrel life

[ShootDots]

Obviously, the larger the case, the more the powder. The more "overbore" the case, generally the higher the pressures developed to push a bullet faster. The more powder, coupled with higher the pressures, will burn out a barrel faster. However, I think there is more to it than that. I had a 22-250 that I primarily used for Prairie Dog hunting. When that barrel went south, it had in excess of 4000 rounds thru it! Earlier this year, I just disposed of a .260A.I. barrel that went south at 1050 rounds! How can this be?? I think that just as importantly as "heat / pressure" is barrel steel.. If you have, for lack of better terminology, "strong / better" barrel steel in your barrel, your barrel WILL last appreciably longer! Conversely, "bad" barrel steel will curtail a barrel's accuracy level in very short order indeed! I have a friend of mine who shoots F-Open and has for years. He shot with a fellow who shot an amazingly accurate 6mmBRX. He stated that that rifle shot lights-out for nearly 3500 rounds! His friend was running 107SMKs slightly above 3000 f.p.s. NO WAY should that last that long>>>>but it did! It is without doubt that running high pressures with copious amounts of powder will shorten barrel life considerably, especially when used in competition where long shot strings are the norm. However, I am convinced barrel steel is of just as great of importance..

 

[Bart B.]

Obviously, the larger the case, the more the powder. The more "overbore" the case, generally the higher the pressures developed to push a bullet faster.

I disagree.

Over-, at- and under-bore cases for a given bore size are often spec'd to about the same max pressure levels yet shoot a given bullet faster as charge weights and case volume increase. 7-08 Rem, 280 Rem and 7mm Rem Mag are exmples.

 

[ShootDots]

I disagree.

Over-, at- and under-bore cases for a given bore size are often spec'd to about the same max pressure levels yet shoot a given bullet faster as charge weights and case volume increase. 7-08 Rem, 280 Rem and 7mm Rem Mag are exmples.

So you are saying that a 7mm-08, shooting 180 class bullets at 2700 will burn out a barrel at the same rate as a 7mm Rem Mag shooting the same bullets at 3000? These velocities are out of a 30" F-Class barrel..

 

[Dusty Stevens]

So you are saying that a 7mm-08, shooting 180 class bullets at 2700 will burn out a barrel at the same rate as a 7mm Rem Mag shooting the same bullets at 3000? These velocities are out of a 30" F-Class barrel..

And a 6x284 has about half the life of a 6br shooting the same bullet.

 

[dcali]

You guys are talking past each other. I believe you’re saying the same thing. Peak pressure is limited by brass strength, so in that sense, Bart is correct. Of course, a larger case can maintain a higher pressure longer by ussing a slower powder and a longer barrel, increasing velocity and reducing bore life.

 

[Bart B.]

So you are saying that a 7mm-08, shooting 180 class bullets at 2700 will burn out a barrel at the same rate as a 7mm Rem Mag shooting the same bullets at 3000?

No, the 7 mag barrel lives in match rifles was about 800 rounds. 7-08 match barrels about 2500 rounds. When my friend set the 1000 yard record at the 1970's nationals, the 7 Rem Mag he borrowed had a couple hundred rounds through it, it's owner wanted him to shoot it during its best accuracy time. It was testing sub MOA at 1000 then, but opened up to over 1.5 MOA at 800+ rounds.

Check my barrel life table below.

 

[mikecr]

The ones I would start with would be bore circumference, powder charge, and bullet weight.

You don't need bullet weight either. Powder type & amount are tied to bullet weight.
Bullet bearing length, itself, means nothing toward anything. BC, barrel life, stability,, none of it.

 

[mikecr]

Peak pressure is limited by brass strength

Wrong. Viable peak pressure, if that's what you're talking about, has little to do with brass strength. ANY cartridge brass has relatively little strength. It's about chamber area -vs- that chamber's support.
And counter to mentioned elsewhere, overbore cartridges do not lead to higher pressures, viable or otherwise. The highest viable pressures you'll see run are with competitive 6PPCs(an underbore). And even while they are tiny, and burn little of one of the coolest burning powders in existence(N133), they rarely hold competitive barrel life past 1,000 rounds.

There is more to it than folklore & rules of thumb.
Also, if somebody's steel is lasting longer than others, wouldn't it make sense that we'd all know about that by now? Is any of that notion really true?