I do think This short review applies to all AEG SCARS, but this experience comes from the Echo1 model. Do not get one. I have just spent 7 hours working on the most poorly designed AEG I have yet seen. Performing any maintenance on this gun is absolute torture, let alone upgrades. Due to the way this gun's body is designed, removing the gearbox takes an effort beyond frustration. Just don't even bother.You literally have to fight this gun tooth and nail to get the gearbox out of the body, prying, bending, and cursing all the way.