The point with the MW2 M4 is that it's heavily modified. I've just done some digging, and it turns out the M4 has a ARMS Selected Interface Rail [http://images.trademe.co.nz/photoserver/tq/89/101676889.jpg](The continuous rail attachemnt you mentioned), a PRI folding front sight [http://www.mountsplus.com/miva/graphics/00000001/PRI-FUP-001.gif] and an ARMS #40L rear sight [http://www.mountsplus.com/miva/graphics/00000001/40L.gif](The HK-esque folding sights).MaxMees said:Hmm I don't know, it has the continuous rail across the top and Heckler and Koch flip-up sights.Atvomat_Nikonov said:Eh, according the the CoD Wikia it's an M4A1 with some crazy RIS attachments on it. I'm aware it looks similar to the 416, but if it was the 416 I'm pretty sure they would have called it that.MaxMees said:You know the M4 in MW2 is just a HK M416 right? It's already a preset on PMG.Atvomat_Nikonov said:The M4 was a quick edit. Just changed some of the parts to tan color, removed the carry handle, added a rail attachment to the end of the handguard and tried to recreate the S.I.R that is mounted on the M4 in MW2. I also re-colored the bottom half of the reciever in Paint as well.
You can tell that it is the M4 though, as it has little defining features that are only present on the M4 and not the HK416. The main one being the HK fire selector switch being absent.
If you put all of those parts on a standard M4A1 you'd get an M4 that looks a bit like a HK416.