ViolentPanda
Hardly getting over it.
Daily Mail decided a little airbrushing was needed to get the full effect out of the weaponry porn.
View attachment 107732
Fuck me, some right old bollocks.

The M4 isn't "single shot", the carbine variant is semi-automatic - it fires as fast as you can pull the trigger.
The version in the pic isn't "heavily modified", it's a stock item that allows attachments from a host of manufacturer-provided accessories, from torches to grenade launchers, and the sight is standard issue.
The M4 carbine isn't "popular with US armed forces", it's the issued weapon to the USMC, and the army is gradually upgrading all regiments to M4s from the M16-A3 and A4, except that they have selective-fire models, not the semi-auto carbine model.