I'd advise you not to make random stat mags unless it will help max a certain class.
If you plan on selling mags I would advise you on the following...
(Sato/Nidra)
5/145/50/0
5/150/45/0
5/0/45/150
5/0/50/145
(Easier with Sega System mags)
5/195/0/0
5/0/195/0
5/0/0/195
There is also a application called MagFarm which is useful for mag making