It's actually nice to have a gas blowback pistol to use as a primary in CQB games. The only problem is you get outgunned due to higher capacity magazines in carbines and SMGs used by other players. If you want your Marui Hi-Capa 5.1 to go head to head against the bigger guns, you need a higher capacity magazine. ProWin just released two magazines that can help you with that, and you can choose between the 40 or 30 round magazine.

Both of these are right now in stock at eHobby Asia.