I doubt many people would notice the difference if any existed. At one time, some custom 'smiths catering to the PPC crowd machined cylinders down to barely clear the nose of wadcutter target loads. The barrel shanks were extended to make the jump to the rifling the length of the forcing cone plus a few thousandths. Since there's been no tidal wave of copies of this type of work, I expect any difference wasn't worth the machine time.

Moving the bullet forward also reduces the amount of force necessary to pull the bullet from the case, which adversely affects the powder burn. In short, leave well enough alone.