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  #1  
Old 01-13-2021, 9:31 PM
1911man 1911man is offline
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Default 6.5 CM vs 308 barrel wear

I have been doing some research and it seems that the CM wears out the barrel on an average of 5k rounds and the 308 on average wears out about 10-15k rounds. The velocities are not that much apart. Could it be there is more surface area touching the lands and grooves thus wearing the barrel more?
I am thinking about cutting a AR 10 in 6.5 CM down to 16” from 20” because I will be using the rifle for hunting, and steel out to 500. ( No I am not going to be shooting elk at 500). I am thinking about after the CM wears out rebarreling to a 308, but that would mean stocking up on 308, and no I don’t reload.
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  #2  
Old 01-13-2021, 9:52 PM
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it is more about heat and pressure distributed over a smaller area.
rate of fire is an even larger factor.
jmo, but unless you hunt in high wind conditions, 6.5cm isn't going to give you that much of a ballistic advantage.
then again, a new barrel isn't that much and the 6.5cm will be easier to shoot.

Last edited by theLBC; 01-13-2021 at 9:55 PM..
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  #3  
Old 01-13-2021, 10:19 PM
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Quote:
Originally Posted by 1911man View Post
I have been doing some research and it seems that the CM wears out the barrel on an average of 5k rounds and the 308 on average wears out about 10-15k rounds. The velocities are not that much apart. Could it be there is more surface area touching the lands and grooves thus wearing the barrel more?
I am thinking about cutting a AR 10 in 6.5 CM down to 16” from 20” because I will be using the rifle for hunting, and steel out to 500. ( No I am not going to be shooting elk at 500). I am thinking about after the CM wears out rebarreling to a 308, but that would mean stocking up on 308, and no I don’t reload.
Smaller bores wear out faster when similar amounts of powder are burned.
This is because the powder generates heat and the heat and powder/gas flow erodes the barrel.

Barrel life depends on your definition of what "worn out" means.
Everyone has a different idea.

If you are looking for peak accuracy, a 6.5 Creedmoor barrel would typically be changed out at around 2300 rounds by most match shooters.
A 308 barrel would typically be changed out somewhere around 3000-4000 rounds by a match shooter.

The much higher round counts that you are quoting will have MUCH larger groups, like "minute of man at 200yds" levels of accuracy instead of minute-of-egg at 200yds like a match shooter would require.
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Old 01-13-2021, 10:21 PM
1911man 1911man is offline
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As I was doing the research, the article did not address the rate of fire. I am assuming the rate of fire was the similar for the purpose of the article. The article suggested the research was from Precision tactical shooters.

Last edited by 1911man; 01-13-2021 at 10:26 PM.. Reason: Spelling
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Old 01-13-2021, 10:32 PM
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I don’t get 16” in 308.

I really don’t get 16” with 6.5 creedmoor.

I know it’s probably not much of a drop in velocity - just a big fireball at the end.


It’s your call as to what your want.


As I understand it, the 6.5 benefits from a longer barrel.




Anywho.... 2,000 rounds of creedmoor is $4,000 or so


I would ask if you considered- buy the .308 upper or barrel you want now in the length and configuration you desire.

Sell the un chopped 6.5

Save big $$$ switching to .308 today and not chopping the 6.5


If you don’t reload- people will want your once fired brass. Donate or sell
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Last edited by hermosabeach; 01-13-2021 at 10:46 PM..
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Old 01-13-2021, 10:42 PM
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Quote:
Originally Posted by 1911man View Post
The article suggested the research was from Precision tactical shooters.
"Precision Tactical" is an oxymoron.
Precision and Tactical are generally the opposite ends of the accuracy requirement spectrum.
Tactical shooters are usually worried about minute-of-man at 200yds.
Precision shooters are usually worried about minute-of-egg at 200yds.
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Old 01-13-2021, 10:46 PM
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Thanks Randall. I did not know the heat, gasses and the diameter of the round made that much of a difference. So the 6mm CM barrel would need to be replaced sooner?
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Old 01-13-2021, 10:57 PM
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Quote:
Originally Posted by 1911man View Post
Thanks Randall. I did not know the heat, gasses and the diameter of the round made that much of a difference. So the 6mm CM barrel would need to be replaced sooner?
1600 rounds is a typical "best accuracy" barrel life for a 6 creedmoor.
You hear all sorts of exagerations from people about them lasting 2000-3000 rounds, but guys that actually shoot matches and value accuracy know when a barrel is toast and pull it off.

Play with this:
http://accurateshooter.net/Blog/barrellifeupdate.xls
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Old 01-13-2021, 11:24 PM
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Thanks again. Looks like a good read.
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  #10  
Old 01-13-2021, 11:29 PM
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I was told if I send the upper to the manufacturer they would swap the barrel to 308 at any length for $350.
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