Mags aren't serialized, though.
I've ben on FTXs where mags have been dropped in defensive positions with very long grass. In one case, I had a 30rd mag fall out of a pouch- not sure how the heck it got open. Anyway, mine was one of two mags dropped that day. Both were searched for, but not extensively- there was an Ex to run. Anyway, the next evening someone was walking through our defensive position and ended up booting my dropped mag. It was nice to get it back. This was on my SQ, and I ahd the fear of God in me for losing that thing. I was told by my Sgt that it was a serious thing, but that it happened- don't crap my pants in fear for my life, but be bloody careful about it in future.
Regardless, you'll never have to worry about teh mag pouches on the webbine in a mission- if you don't have the new TacVest yet, you'll definitely get it before going anywhere. They're easier to do back up.
That being said, I actually find the palcement of the mag pouches a minor pain in the arse on those; with the old pouches you could yank it open and load a mag int wo seconds if you had to. But with the new ones, undoing the buckle and then opening the pouch are two slightly seperate motions that eat up a few valuable frctions of a second, and more importantly, you can't do it silently. Bloody Velcro.
marshmanguy , when you're out of basic training, or at least into doing section attacks on your SQ, you'll learn that spent mags simply don't go back into the pouch when you're in the middle of an ettack. Two popular methods are either showing them in a pocket- combat pants pockets, for instance, or tunic pocket if you're using the odl webbing, or (my preferred method), dropping them down your shirt. With the waist drawstring tied up, the mag won't fall out, and it's pretty easy to fish them out and put 'em away when you get a second. I havne't yettried this with winter gear on- hopefully my patrol hide will get bumped on my Ex this weekend and I'll get to have a bit of fun (My unit is all recce all weekend), so maybe I'll be able to back to you on winter alternatives.
You're doing the right thing coming on thsi site and asking people- all these minor hints and tipps add up quickly to a much easier experience when you're in the field. I've learned tons from these people.