Lack of follow-through is sort of "relaxing" the concentration on holding the gun on aimed point on the target. This allows the muzzle to drop - the start of the drop being often before the trigger is actually released - or the bullet has cleared the barrel - leading to hitting low.
While recoil will upset the sight picture, correct follow-through is sort of like shooting, and imagining the gun will not recoil - and that you are going to hold it with sights aligned on the precise aimed point on the target for a second or two after the gun has fired. Of course the gun in recoil will upset all this - but holding with follow-through as such eliminates any chance of muzzle drop before the trigger is released and the bullet is clear of the barrel.
While recoil will upset the sight picture, correct follow-through is sort of like shooting, and imagining the gun will not recoil - and that you are going to hold it with sights aligned on the precise aimed point on the target for a second or two after the gun has fired. Of course the gun in recoil will upset all this - but holding with follow-through as such eliminates any chance of muzzle drop before the trigger is released and the bullet is clear of the barrel.
