All I can say is that in our house we have a few mags from guns we bought
but best mags are dytac M4's that had a tiny squirt of dare I say it:
WD40
this was used in the past and since have well been run through - jeez they have had some bb's through them
(so I really doubt if there could be any of that left in any of them - trigger happy doesn't cover my playstyle at times)
I don't say WD ya mags like I did but these are well run-in but feed flawless in every gun we use them in
some G&G & ICS ones are never as good as our old faithfuls - but then some mags work in some guns
and some suck in others we found - but these are run-in to say the least
some mags might be fine "as is" - hence I say just try them first - see if the bb's load/feed smoothly when you start
to fill - rising in mag ok and not snagging - give them a go as is n see before you go nutz with any form of lube
(always a risk of going ott with any lube so as saying goes
If it ain't broke - don't try to fix it, so try try them as they are first