Okay, apparantly exaggerations are taken literally here... But I should point out that USMC basic training requires each future Marine to hit a man-size target at 500 yards with an M4 carbine. Sniper rifle range (guns like M40s, any of the Arctic Warfare series of rifles like the L96 and L118, and CheyTac M400s) is currently defined by most militaries as 600m+, marksman rifle range (despite what games will tell you, the M39 EMR is a marksman rifle, as is the SVD Dragunov) at 300-600m and rifle range (this is M4s and M16s, basically) is 0-300m. Honestly, if you shoot actual rifles, 200 yards is not difficult. In my experience, I can consistently shoot 2 or 3 MOA (that's minute-of-angle, look it up, it's how accuracy is measured) with a bolt-action .22 Long Rifle, standing, barrel-rest (that's not too dissimilar from your precious bipods) with open sights (which are different than iron sights, since open sights are a category of simpler iron sights that are less accurate). So hitting a target at 200-400 yards with a sniper or even a marksman rifle nothing special, and could probably be replicated in real life by someone with only minimal knowledge of guns.

TL;DR: The point is, the game forces you to mount scopes and bipods and go prone to hit targets that are not difficult to hit with a CQB-outfitted M4A1 in real life. (Before you start doubting my credibility, I am not in the military, nor have I ever been, or ever can be, since I've been type-1 diabetic since I was 13, but I am a gun nut and have shot various AR-15s and AR-pattern rifles and I also shoot competition on occasion.)

And calling the M4A1 a "carbine" in that game is bullshit. Especially since, I believe, the AK-74u is in that same category, despite being classified by both NATO and Russia as an SMG. "Carbine" does not have much meaning anymore, since the only difference between an M16A2 and an M4 is four inches of barrel and only slightly less accurate. Following the 5.56mm revolution that came after the M16 and M16A1 were introduced, lighter guns with shorter and shorter barrels have been the norm. Most standard rifles issued to modern militaries today have barrels shorter than 18 inches (approximately the length of an M16 barrel) and, in the US military, the M16 is all but being replaced by the M4, because you have a major advantage in mobility and versatility with 4 inches cut off the barrel and full-auto capability, while retaining most of the accuracy of the longer M16.

Since we're talking about a video game, in Operation Flashpoint: Red River, I made a 550m headshot with an M16A4 with an Aimpoint red dot sight (which is the kind people actually use, not the tiny little ones in CoD and Battlefield, look them up, they look like scopes, but actually offer no magnification) and an M203 grenade launcher (which increases the weight of the gun and makes it less accurate when standing or crouching), as I said, 550m away, firing from the ground through a second-story window about 15 feet above me (which affects how the bullet drops), crouched, with the gun on semi-automatic. (All of these on Xbox, with a joystick, so less accurate than a mouse, of course)

TL;DR Part II: Basically, for a game that constantly touts itself as being "authentic" and "realistic," it... (puts on sunglasses) falls short.

YEEEEEEEEAAAAAAAHHHH!!!!