There is generally little reason to shoot straight upward for obvious reasons, but it is nice to know your revolver will fire no matter where you are pointing. The other day I was laying back on a recliner doing some dry fire practice with a 625-6 and I noticed that when aiming directly upward (90 degrees or more from the horozontal) the gun would randomly bind up just before the hammer would fall on DA or before coming to full cock on SA. The gun functions fine when cycled in any 'normal' position. The only part I could think of that rattles around inside a Smith and might be effected by gravity is the hammer block. I removed the hammer block and found under magnification a burr/imperfection that was binding at the edge of the cutaway track in the sideplate. Stoned away the burr and everthing was OK. Never heard of this happening before but I quess if you are not aiming at a spot on the ceiling, you would never notice.