Sounds like a great improvement in the performance of the first gun. While shorter barrels are stiffer, an improvement like that is likely due to removing a worn portion of the muzzle. In any case, great job.I just shorted a barrel from 29 to 20 inches. It use to be a 1.5 inch gun, its a jagged hole gun now. For the little you loose in velocity, and its minimal you gain a lot more in rigidness of barrel and maneuverability. We also have a Mauser actioned 308 that we took down to 18 inches, it to has not suffered in accuracy. I believe for 308 its 30 fps lost, or gained per inch, depending on weather your going longer or shorter.
24 is about the minimum length for magnum calibers but for the 308 its not really needed. The Army and Marine core sniper rifle is only a 20 inch barrel after all.
If you do go with an 06 for your next rifle get the 26 inch Remington varmint contour or similar to it. Load up some 308 208 grain Amax bullets, there F'in magical when combined.