The 308 is a fairly efficient cartridge at burning powder and accelerating the projectile down the barrel. Meaning for most factory loads its burning almost all of the powder as it gets to the muzzle.
There are other cartridges that have much larger cases and same caliber that are overbore or close to overbore. general O-ratio is calculated by dividing the volume of the case by the area of the bore. The higher the ratio the more overbore. The 308 is at 7.66/1 on the metric chart placing it on the lower end of the overbore chart.
All that to say that the 308 does not need as long a barrel to utilize a slower burning powder to avoid over pressure to achieve higher velocities.
If you plan to reload at any point I would recommend a 22-24" barrel. It will give you more versatility in building a load that suits your needs and should handle the 180 weight bullets with a 1-10 twist.
I couldn't find it again but I read an article recently where a guy did a velocity test where he fired a string of shots recorded the velocity and then cut the barrel down by an inch each time. He recorded increased velocities at a shorter length than the original 26" barrel, I believe he was between 20 and 23 when he recorded maximum velocity.
Hope this helps, if nothing else I entertained myself for a few minutes.
There are other cartridges that have much larger cases and same caliber that are overbore or close to overbore. general O-ratio is calculated by dividing the volume of the case by the area of the bore. The higher the ratio the more overbore. The 308 is at 7.66/1 on the metric chart placing it on the lower end of the overbore chart.
All that to say that the 308 does not need as long a barrel to utilize a slower burning powder to avoid over pressure to achieve higher velocities.
If you plan to reload at any point I would recommend a 22-24" barrel. It will give you more versatility in building a load that suits your needs and should handle the 180 weight bullets with a 1-10 twist.
I couldn't find it again but I read an article recently where a guy did a velocity test where he fired a string of shots recorded the velocity and then cut the barrel down by an inch each time. He recorded increased velocities at a shorter length than the original 26" barrel, I believe he was between 20 and 23 when he recorded maximum velocity.
Hope this helps, if nothing else I entertained myself for a few minutes.
