Not sure about the mags and rail issue, but in terms of upgrades, I normally shove in a Prommy tightbore, but I've found the most useful one is putting in a larger hop nub, as in my stock Type 97, I had to adjust the hop dial to 8-9, whereas with th new hop nub (I'm currently using a Madbull blue 60 hop nub and rubber) I only have to turn it to about 3-4.