Great gerabox for your aegs. I am pretty confident that this sucker can hold an m120 in it eith little to no problems. I ahve an ICS mp5 a4 and it ahs an M110 in it and it is shooting at 340 fps. If you want a gerabox that can handle upgraded springs and internals then this is your answer to your problems. Unlike most other companies besides of course Systema this gearbox is the best you can get for the price.