question about barrel life

B

Beanstalk

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Seasons greetings to all:

Recently I have been reading about the characteristics of several long distance cartridges. A number of people have mentioned that a 6.5 Creedmoor cartridge will wear out a rifle barrel significantly faster than a .308 W will. Can anyone explain ( in simple, layman's terms ) what causes this? Why does the Creedmoor round chew up a barrel faster than the .308 W ?

Many thanks for your insight.

B
 
The .308 is a very "forgiving" cartridge. Anytime you start comparing other (smaller caliber)cartridges to the .308 in regards to barrel life, the .308 will most likely win.
I wouldn't spend much time worrying about barrel life since barrels are not that expensive these days.
 
Too many generalities. Let's see if I can add a small amount of perspective here.

There are some cartridges that are harder on a barrel than others. Generally speaking, cartridges that burn alot of powder, yet use a (relatively) small diameter, light bullet....tend to produce barrel erosion at a faster rate than cartridges with less powder/ heavier, larger dia. bullets. The term often applied is "over bore" cartridges....as in, the case ( where the powder is) is MUCH larger than the bore itself.

The reason for this general characteristic of "over bore cartridges" is pretty easy to understand. More powder burnt, for a given bullet weight....therefore, greater hot gas induced barrel erosion. Smaller bullet....therefore higher velocity and higher levels of friction, as a result. Smaller bore, but bigger case.....higher chamber pressures, in some circumstances.

Now, the caveats - and there are a lot of them. This comparison, between "over bore cartridges" and more conventional ones, is real...but it does NOT operate in a linear fashion. In other words, you cannot do a direct comparison, based on some derived ratio, such as cartridge case dia. vs. bullet dia., etc. etc. There is A LOT more to it than that. I could go on, about 20 pages worth...and still not fully explain it. So, I will try to keep it simple.

So, for purposes of the OP's specific reference....the 308 Win. vs. the 6.5 Creedmore....which will wear out a barrel faster ? The answer is NOT clear. Simply going by the simple concept of the "over bore cartridge", as stated above, would suggest that the 308 barrel might last longer. BUT, there are LOTS of other factors....such as the specific loads used, the barrel composition, how many shots fired before letting the barrel cool down, etc. etc.

The short answer, on this question, really is : no one can say, definitively, when comparing two specific barrels - because there are too many specific variables.

But, in the real world, with cartridges loaded to the SAME pressure for comparison....and holding ALL the other variables as close to the same as possible... in many circumstances....the 308 would TEND to last longer. No guarantees, though.
 
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By the time you wear a barrel out you'll have spent so much on ammo that the cost of a replacement barrel will look like a drop in a bucket.
 
The answer is "overbore". Smaller caliber rifles that use equal or more powder will wear out barrels faster. The 308 is noted for being one of the rounds that do not wear out barrels very fast. A 243 on the other hand uses the same case as 308, but is 24 caliber instead of 30 and tends to shoot out barrels faster. Having roughly the same amount of powder burned in a much smaller barrel increases heat in the 1st few inches of barrel.

The 6.5 is 26 caliber and in theory should split the difference between 243 and 308 as to barrel life. But the 6.5 is still a relatively low powder capacity case and 6.5mm isn't that small so barrel life may be shorter than a 308, but will still be good. In theory a 25-06 or 270 should burn up barrels faster. A 270 is 6.8mm with a lot more powder capacity. 25-06 is noted as a barrel burner, but it is still somewhat popular as a hunting round.

Not something I'd worry about. 1st you have to define useful barrel life. For a long range benchrest shooter a rifle may be worn out after 5000 rounds, but the same barrel may still be perfectly acceptable as a hunting rifle for 10,000-15,000 rounds. Anyone who can afford to put 5000-10,000 rounds through a barrel can afford to buy a new barrel. And I'd expect a 6.5 Creedmoor to last a lot longer than 5000 rounds.
 
And the 6mm Creedmoor will have it's throat eroded faster than the 6.5 for the reason (bore diameter) mentioned above. Nearly identical powder load, lighter bullet= slightly less recoil.

Barrels are like tires on a car....
 
Wearing out a rifle barrel is a relative term. Accuracy means a totally different thing to a deer hunter than it does a target shooter. And another thing entirely to the bench rest guys. A hunter doesn't need or really care if his rifle will only shoot 2 or 3 MOA, as long as it does so consistently. Target shooters, especially a bench rest guy, would have a stroke over a rifle that shoots like that.
It also takes a lot of shooting to do too.
"...Too many generalities...." Lotta fairy tales regarding barrel life too. Don't really think the 6.5 Creedmoor has been around long enough(10 years old this year) for there to be enough or any recorded data.
 
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