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Discussion Starter #1
First I hope I am posting in the correct forum. I've been looking at a RPR for awhile now and I may purchase one as my local gun shop may have a few coming in. I started doing some research on 6.5 Creedmore and found that the barrel life is on average between 2,000 to 3,000 rounds while a .308 rifle will have an average life of 10,000 to 15,000 rounds. My question is, why does the 6.5mm wear out a barrel so much faster than say the .308 ?

Thanks....
 

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It depends on your definition of "barrel life". The 6.5 Creedmore is usually used as an accurate long-range target round and it's barrel is considered worn out when the guilt edge accuracy is no longer available. The .308 can also be a fine target round but most users use it for hunting, short range target and general range use so it's still fine for many uses even when it's best accuracy is gone. The .308 uses about the same powder charge as the 6.5 but has a larger bore so the powder gas erosion takes a bit longer to do the damage but not 5 times as long.
 

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At current 6.5 Creedmore factory ammo prices, that means a barrel is good for $2000-6000 of ammo.
 

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When you think about "barrel life", the first thing that comes to mind is bore wear. Although bores and rifling do wear, the major part of the problem with barrel life is the throat. This is the area just in front of the cartridge where throat erosion takes its toll. What happens is the eroded throat allows a bullet to get out of alignment with the bore when the round is fired. This damages the bullet and makes it fly goofy. As throat erosion gets worse, accuracy will also get worse.

The reason why some barrels experience a shorter life is simply due to the cartridge's shoulder angle and of course the amount of powder. The shoulder angle works somewhat like a lens and is supposed to focus pressure on the base of the bullet. If the pressure focuses on the throat instead of the bullet base, it will cause flame cutting AKA throat erosion.

The worst cartridge I know of for throat erosion and a short barrel life of about 500 rounds is a 264 Win Mag. Cartridges with a long brass neck, such as a 30-'06 seem to last the longest, in excess of 15,000 rounds in a bolt action rifle. Semi-auto 30-'06 rifles don't fare quite as well so they typically last about 10k rounds. Some of the common "barrel eaters" are: 243 Win, 220 Swift, and 22-250 Rem. Some of the longer barrel life cartridges are: 30-'06 Spr, 7x57 Mauser, 5.56 / 223 Rem, 308 Win, and 6.5x55 Swede. You may see a pattern here .... most cartridges developed for military use have a long barrel life.
 

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This Link to Accurate Shooter article has a nice chart and article on over-bore and barrel burners.

In retrospect, I wish I had opted for the Savage 223 single shot instead of the Savage 243 long range precision that I bought.
I was seduced by the superior ballistics of the 243, but was not aware it was a barrel burner.
However, I can down load 100 grain bullets in the 243 to somewhat mitigate this.
 

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And don't forget , a large degree of barrel burning reputation boils down to powder selection and velocity goals.
Powder burn rate . pressure curve , you know , all that science stuff.
If your goal at reloading is over the top , set your hair on fire with every pull of the trigger , maximum velocity at all cost ,,,,,,,,, your gonna have a HIGH chance at having a barrel burner.
This stuff goes all the way back to the 220 Swift . And while not exactly barrel burning the same reloading misdirected goals killed the 357 Max.
Exercise a little caution in powder selection and avoid extreme goals and you will get a good lifespan out of most cartridges
 

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needsmo, Some interesting things as they relate to throat erosion. All smokeless powders, no matter what their burn rate is, will develop a burn temperature between 5000 and 6000 deg F. Burn rate is important because it also affects burn time. Slow burning powders apply intense heat for a longer period of time than faster burning powders, even though they burn at about the same temperature. Unlike handgun powders where there is a very significant difference in burn rates, rifle powders have different burn rates too but the burn rate range is not as dramatic. As an example, Bullseye pistol powder takes less than an inch of bullet travel to totally burn up. H-110 (magnum pistol powder) takes about 15" of bullet travel to burn up. Faster burning rifle powders take about 20" of bullet travel to burn up whereas slow burning rifle powders can take up to 26" of bullet travel to burn up. If you do the ratios, handguns would be 1:15 versus 20:26 for rifles. By reducing the powder charge, you also reduce the time it takes to get a total burn but the temperature of the burn remains the same.

Lighter weight bullets require less powder and develop higher velocity so that's one of the key issues for extended barrel life. This combination of less powder and higher velocity means less heat exposure time, thus less flame cutting.

Back to the basics ..... throat erosion is primarily caused by where the brass case directs the flame. No amount of reduced powder charge or a different burn rate will eliminate throat erosion .... but it will help reduce it. If you have a known "barrel burner", try to use faster burning powders and lighter weight bullets to help extend barrel life.
 

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a .308 rifle will have an average life of 10,000 to 15,000 rounds.
I read this last night and read it again today, so I have to ask..........are you sure about that? I'm not buying it if we're talking about MOA accuracy at any given range, maybe "Minute Of Paper Plate" accuracy.

I have a bunch of friends who are F Class shooters......they demand .5 MOA out of their rifles, some barrels have lasted 2400 rounds some have lasted 4000 rounds. It's kind of like a car, it all depends on how you drive them. But so many other things come into play with barrel life, cartridge design, what kind of powder, how fast are you driving the bullet, shot cadence and the barrel it's self. A Krieger barrel is made with harder steel than say a Bartlein barrel, that said the Krieger stands a better chance of lasting longer. You can also throw in excessive cleaning and improper cleaning methods into the mix for reduced barrel life.

Then there's the overbore index, which is not chiseled in stone, but more a predictor for barrel life. A barrel in the right or wrong hands, (depending on how you look at it) can be burned up before it's time. I know a guy who toasted a .22-250 in under 1000 rounds on a PD hunt......he only brought one rifle with him.

The .308 Win has an index of 751.6 where as the 6.5 Creedmoor has an index of 959.6, Here's the math on the Creed.........

3.14(.264 x .264)/4 = .05471136


52.5/.05471136 = 959.58


The reason a .243 (an index of 1164.4) is a burner is because of the case capacity in relation to the bore..........you're pushing a lot of powder out of a little opening. Another example would be the .30-06 at 915.4, its above 900 but under a 1000. But when you neck down the 06 to a .270 the index rises to 1095.2, drop it down to a .25-06 and your index is 1272.3.

If anyone is interested as to the index on a .264 Win Mag...............it's 1454.9.
 

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Mark204, Barrel life for 30-'06 (7.62X63) and 308 Win (7.62x51) are based on military battle rifle standards, not MOA long range competition like you are used to. The exception being sniper grade rifles where accuracy standards are probably the same as your long range specs. With hunting rifle barrel life, if a gun can maintain "kill zone" accuracy at 250 yards, it's good to go. BTW the kill zone on a deer is about 8" so at 250 yards, that would be about 3.2 MOA .... a far cry from your .5 MOA.

The overbore index is interesting but it doesn't address how the flame exiting the case mouth focuses like a lens due to the shoulder angle. That said, it's probably a decent judge when comparing different cartridges. Yes, the metal used in a barrel can make a very notable difference in barrel life. It only makes sense that alloys more resistant to heat damage will last longer. With "off the shelf" rifles, you don't get the exotic alloys .... you just get what ever the manufacturer uses. With custom made rifles or replacement barrels, you can get what ever the thickness of your wallet will support.

The key points here are .... your input is based on precision long range target shooting and your conclusions are very respectable, however most of us use standard production rifles for hunting or casual target practice .... a quantum different in virtually all respects.
 

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Iowegan, if one applied the same military battle rifle standards to the Creedmoor your round count/barrel life will increase. The reason most swap out their barrels in the 2000 to 3000 is because it has lost its sub-MOA accuracy, not because it’s lost it’s minute of paper plate accuracy, (8”s).

My soul reason for referencing F Class was to show that the .308 is NOT getting 7 to 8,000 rounds of more barrel life than a Creedmoor, maybe 1000, maybe 1500, but not 8,000.

Yes shoulder angle does factor in, I omitted that because you covered it in an earlier post.

I agree, there’s a big difference between precision shooting and hunting accuracy, but when people see “2000 to 3000” rounds they assume it’s hunting accuracy which isn’t the case.

I think a .308 could out last a Creedmoor, but by how many thousands of rounds? I know I’ll never find out because as soon as my Creedmoor shoots over MOA the barrel will end up in the trash.
 

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Discussion Starter #11
When you think about "barrel life", the first thing that comes to mind is bore wear. Although bores and rifling do wear, the major part of the problem with barrel life is the throat. This is the area just in front of the cartridge where throat erosion takes its toll. What happens is the eroded throat allows a bullet to get out of alignment with the bore when the round is fired. This damages the bullet and makes it fly goofy. As throat erosion gets worse, accuracy will also get worse.

The reason why some barrels experience a shorter life is simply due to the cartridge's shoulder angle and of course the amount of powder. The shoulder angle works somewhat like a lens and is supposed to focus pressure on the base of the bullet. If the pressure focuses on the throat instead of the bullet base, it will cause flame cutting AKA throat erosion.

The worst cartridge I know of for throat erosion and a short barrel life of about 500 rounds is a 264 Win Mag. Cartridges with a long brass neck, such as a 30-'06 seem to last the longest, in excess of 15,000 rounds in a bolt action rifle. Semi-auto 30-'06 rifles don't fare quite as well so they typically last about 10k rounds. Some of the common "barrel eaters" are: 243 Win, 220 Swift, and 22-250 Rem. Some of the longer barrel life cartridges are: 30-'06 Spr, 7x57 Mauser, 5.56 / 223 Rem, 308 Win, and 6.5x55 Swede. You may see a pattern here .... most cartridges developed for military use have a long barrel life.
Thank you for the clear and in-depth answer, much appreciated.
 

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Discussion Starter #12
When you think about "barrel life", the first thing that comes to mind is bore wear. Although bores and rifling do wear, the major part of the problem with barrel life is the throat. This is the area just in front of the cartridge where throat erosion takes its toll. What happens is the eroded throat allows a bullet to get out of alignment with the bore when the round is fired. This damages the bullet and makes it fly goofy. As throat erosion gets worse, accuracy will also get worse.

The reason why some barrels experience a shorter life is simply due to the cartridge's shoulder angle and of course the amount of powder. The shoulder angle works somewhat like a lens and is supposed to focus pressure on the base of the bullet. If the pressure focuses on the throat instead of the bullet base, it will cause flame cutting AKA throat erosion.

The worst cartridge I know of for throat erosion and a short barrel life of about 500 rounds is a 264 Win Mag. Cartridges with a long brass neck, such as a 30-'06 seem to last the longest, in excess of 15,000 rounds in a bolt action rifle. Semi-auto 30-'06 rifles don't fare quite as well so they typically last about 10k rounds. Some of the common "barrel eaters" are: 243 Win, 220 Swift, and 22-250 Rem. Some of the longer barrel life cartridges are: 30-'06 Spr, 7x57 Mauser, 5.56 / 223 Rem, 308 Win, and 6.5x55 Swede. You may see a pattern here .... most cartridges developed for military use have a long barrel life.
Iowegan,

Other than a regular cleaning can any maintenance be done to a barrel to reduce or delay throat erosion thus extending the life of the barrel ?
 

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Cleaning really can't reduce throat erosion but it will help the bore. I'm not a bore snake guy, I like one piece brass cleaning rods with a muzzle bore guide. Here's what I do ..... mop the bore with a liberal amount of Hoppe's #9, then let the gun sit with a level barrel for at least 5 minutes. This will give the solvent time to dissolve any powder residue. I then apply more hoppe's #9 and run a bronze bore brush (never use steel or stainless steel brushes) through the bore .... two full back and forth strokes with the cleaning rod secured in a bore guide. Follow up with a dry cloth patch to remove the residue you just broke loose. I then run a cloth patch soaked with Sweets 7.62 bullet solvent in the bore using a cleaning rod. Sweets breaks down any jacket metal that may have been deposited in the bore. Let the Sweets sit for at least 5 minutes, then run a clean tight cloth patch through the bore. Apply a small amount of Sweets to a clean white patch and run it through the bore with your cleaning rod. If the patch turns blue, you have more bullet fouling to deal with. Once a clean white patch comes out with no blue. your bore should be sparkling clean. I finish up with a couple drops of gun oil on a clean patch and make one back and forth pass through the bore and you are finished until you shoot again.

About the only way to reduce throat erosion is to use less powder. This works great with lighter weight bullets because they don't need as much powder to develop the same velocity as heavier bullets. Most reloading manuals do not come close to SAAMI max pressures so even if you load at the high end of the charts, you probably won't do as much throat damage as factory ammo.
 

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Iowegan, if one applied the same military battle rifle standards to the Creedmoor your round count/barrel life will increase. The reason most swap out their barrels in the 2000 to 3000 is because it has lost its sub-MOA accuracy, not because it’s lost it’s minute of paper plate accuracy, (8”s).

My soul reason for referencing F Class was to show that the .308 is NOT getting 7 to 8,000 rounds of more barrel life than a Creedmoor, maybe 1000, maybe 1500, but not 8,000.

Yes shoulder angle does factor in, I omitted that because you covered it in an earlier post.

I agree, there’s a big difference between precision shooting and hunting accuracy, but when people see “2000 to 3000” rounds they assume it’s hunting accuracy which isn’t the case.

I think a .308 could out last a Creedmoor, but by how many thousands of rounds? I know I’ll never find out because as soon as my Creedmoor shoots over MOA the barrel will end up in the trash.
Couldn't the barrel be set back and get another 100 rounds or so ?? Yes, you will lose a little bit of length. But then, I realize I'm a bit of a cheapskate and barrels are not the investment they were 50 years ago. The price of a new barrel won't break the bank.
kwg
 

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Couldn't the barrel be set back and get another 100 rounds or so ??
If your barrel has a high round count I wouldn’t invest the money to have it set back reason being the lands aren’t going to be sharp and crisp anymore. For the price one could add a little more money and have a new barrel installed. You could easily get a couple hundred more rounds out of a barrel by chasing the lands though.
 

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First I hope I am posting in the correct forum. I've been looking at a RPR for awhile now and I may purchase one as my local gun shop may have a few coming in. I started doing some research on 6.5 Creedmore and found that the barrel life is on average between 2,000 to 3,000 rounds while a .308 rifle will have an average life of 10,000 to 15,000 rounds. My question is, why does the 6.5mm wear out a barrel so much faster than say the .308 ?

Thanks....
The short answer would be "Overbore"-i.e. Small bore, used with Large powder charges.
 
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