I've been using the M-416 as a replacement for my sniper rifle...so...yeah. I can use the normal M-4A1, but I've never actually cared for it all that much. Not sure why.
The 416 is actually an H&K gun if I recall, not an Arma. I think they had issues getting licensing, either that or they just don't know their guns. It SHOULD be the HK416 I think.