I ask this question because I've had two barrels on my .223 model 10. The factory barrel had a long throat and so a long distance to the lands. A new McGowen barrel that has a throat is 0.120 inches shorter than the factory tube. Measuring OAL to the lands with both barrels and different bullets revealed quite different results. It seems to me that COAL is something unique to each rifle depending on how the chamber and throat are reamed out. My COAL will be meaningless to someone with a different barrel.

The number that will mean more, is how far the bullet is seated from the lands. Bullet jump to the lands greatly affects the accuracy of the bullet; at least from my limited experience.

So, why list COAL? Because it sounds cool? What?

Thanks,