16" is a lot. One other factor to consider is that the rifles muzzle will rise during recoil while the bullet is still in the barrel. With different recoil the muzzle will rise at a different speeds and rise to different heights before the bullet leaves the muzzle. This can make a difference in impact.
This is more common with handguns and even at that 16" seems like too much.
Have you checked your velocities with a chronograph, or just guessing based on factroy specs or what a loading manual says you should be getting.