Great work man. Since you're adding so much detail, and staying close to a ref, I'll give you some crits here, since I'm a huge
Nothing major, but since you're labeling this AR as a MK18 Mod 0, I went ahead and mentioned it!
Also, since most Mod0 use a KAC compensator, they have to use the KAC suppressor.
unless you're has a AAC flash hider/compensator that's the only way to mount yours :/