ive got an echo m16a4 advanced model the full size. im trying to figure out what gearbox is in it. ive had the gun for almost three years and its held up better then a lot of classic armies and other higher qualtiy guns out there. if some knows what gearbox is in it please let me know, because its a badass m16 and i would like to know for future guns i purchase. if someone also knows about any of the other internal parts in this particular gun, please explain a little bit about that too,just curious, thank you.
