First off, thank you for taking your time to read this and trying to help, this is my first time posting through the forum as well as building a DMR. I've provided a parts list and as much specifications as I can, I really would appreciate any type of advice or opinions. Keep in mind, this is a somewhat budget build. Excuse my noobness as well, I've taken apart m4s before, my base gun as well multiple times so I am familiar with putting it together but I'm sorry for my pleb terminology and ignorance. My base gun is the Apex R5 Battlemod 14 AEG *Info from Evike [I tried to put only relevant points] Inline MOSFET protects trigger contacts One piece metal rotary adjustable hopup unit Reinforced metal gearbox with quick change main spring system and radiused cylinder cuts Pre-installed 6.03mm tightbore inner barrel 9mm bearing bushings and high torque steel bearings Length: 845mm / 940mm, Adjustable Weight: ~2660g Inner Barrel: ~400mm Muzzle Velocity: 390~430 FPS Gearbox: Ver 2 Full Metal, Fully Upgradeable Motor: High Torque Long Type I got this AEG through a mystery box, I was not going to originally build a DMR but after research I completely changed my mind. I did as much research as I could and after hours of trying to plan and budget I came up with this parts list. Lonex Aluminum One Piece Metal Hopup https://www.evike.com/products/35846/ Maple Leaf AST Macaron Bucking -70° https://www.evike.com/products/42460/ RA- Tech Maple Leaf Precision Spacer https://www.evike.com/products/53142/ (Which is the nub... right?) Angel Custom G2 SUS304 6.01 Inner Barrel 510mm (Hollow extended suppressor being purchased to compensate extra barrel length) https://www.evike.com/products/40455/ I'll be running an 11.1V lipo 25c And .28 bbs I plan on making this purchase soon, I've also considered an M130 or M140 spring since I do already have a high torque motor. I would appreciate any help and advice, thank you so much! Update - June 27th, 2018 - Stock internals Gun: Stock hop-up Lower Reciever Air seal nozzle (I think) Stock motor by Classic Army Also marked by Classic Army?