Thread: Seating depth/ Bearing surface

Hi there.
Just watched a video where it was stated (A cardinal rule, though not always achievable. Go figure which is it!) that a projectile should be seated so that it's bearing surface is a minimum of the bore.
Just fired some reloads .243. By my reckoning the load that worked best only had a bearing surface of 5.38mm not the minimum of 6mm. This is on a bolt action rifle. So the question is how critical is this? Does it make any difference if it's bolt action vs auto? And although it may not matter in this case at what point might it become an issue?
Thoughts please.
Cheers FC