A cheap, simple first rifle. The M15A4 takes normal M4 parts. The Lancer 363mm barrel is the M4 carbine length, and the Macaron bucking fixes the stock hop. A 7.4V LiPo is safe on a stock gearbox with no MOSFET. The Amarok 250 round mid-cap fits any M4 or M16 AEG. Example build by LoadoutLab. Every part is listed by its shop as made for this gun. Photo: "Ca m15a4.jpg" by AlecMoody, public domain, via Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Ca_m15a4.jpg). The photo shows this gun model; the parts list is a suggested setup.