A light barrel can sometimes benefit from a full length bed because it can dampen the harmonics which have a more profound effect on a light barrel apposed to a heavy barrel which is more self stabilized. In my experience it depends on the barrel. The easiest way to test it is to shoot the rifle with a free floated barrel, let it cool. Then put a piece of card board under the barrel at the forend, enough to fit tightly, just about an inch long, such as a matchbook or cereal box type material. Essentially false bedding the forend. Shoot it again and see which is the best group. Either decide to bed it or not.