When an M14 type rifle is optimized for accuracy the stock fit will be adjusted (possibly bedded) for consistent downward tension on the front band and the handguard will not touch the stock. This barrel tension is critical to match grade accuracy. Unlike bolt guns, M14s do not shoot well with free floated barrels.
Why? No idea. To paraphrase Dr. McCoy from the original STAR TREK TV show, “Dammit Jim, I’m just a simple country gunsmith, not an engineer.” It works. Trust me.
The front band is sandwiched between the gas cylinder and the barrel shoulder and it will move around a bit on a standard rifle creating inconsistent barrel tension. Many years ago military rifle teams developed methods of “unitizing” the gas system and front band. This means the front band is attached solidly to the gas cylinder resulting in the same barrel tension shot after shot. There are two common methods of unitizing: welding or drill & tap.