Using a properly cleared firearm in the absence of loaded ammunition, hold your pistol in your dominant hand like you were just shooting. Pick up a verified empty magazine as if you are going to load it and stop. Now look at how you grabbed your magazine. place the magazine in your carrier in the most efficient manner, or the manner you feel comfortable with. Where ever that mag sits in it's carrier is probably where you want it.
This is my view of it, too.
We're all different - our bodies (including not only body build, but also flexibility, as well as even what we subjectively feel may be awkward versus easy) are different, so that even without looking at how we place the magazines (and their holders) "clocked" on our body, it's already clear (if not easy) to see that this may affect the "facing" of the bullets in order to have a sensible reload procedure.
But whatever one finally decide to do, the important thing to remember is to do it consistently.
Don't carry your spare mag with bullets forward one day and then bullets facing the back the next. If you carry a double-mag pouch, don't have one facing one way and the other the other.
My first instructor's background included years as a Marine Scout Sniper. Although not known nationally, here in the region among other instructors, his reputation is an excellent one. He prefers his "bullets towards the back."
All he asked us is to try it both ways and to find what we deemed most natural - but that when we found what we preferred, to keep it consistent.
Over the years, I've heard it argued both ways - but I really think that in the end, it's down to personal preference: as long as it's consistent.
