It's a M4a1 Sopmod Block II in my avatar actually and it was planned for Arma II, but it will probably be for Arma III if ever.
At the moment it is on hold since I was trying to make these using the Armed Assault sample models, but to be honost these models are a bit outdated. So I asked around a bit whether I could borrow some models from other great addonmakers, but never got any replies and BIS denied my request for weapon attachments models. I respect them for their choices, but it means I am on my own on this one which wasn't really my aim for this project. My aim was to get some great M4s in-game rather quick.
This is what it looks atm:
Credit to Vilas for his great Elcan Spectre model.