When people ask "what's the best receiver in the game?" they are usually told "AR, or M4X". They say the Assault Rifle is incredibly balanced, and is downright "Over Powered". They don't say such things about the M4X, or why they compare it to such an OP weapon. So what gives?
For the longest, I abided by the "hipfire" crowd. Point, aim, tap in bursts. Other receivers had very wide hipfire spreads. Not so the M4X. This sucker is as tight as a virgin on prom night. You can reliably fire accurately right from the hip, and man, if you aim down sights... pfffft. It has less overall recoil and spread than the Assault Rifle, and can be built to have much much less recoil. It might just be my imagination, but I seem to find what little recoil the weapon DOES have to be more easily controlled than the AR.
The weapon is not without its flaws, however...
All receivers in the game have a specific "recoil pattern" that the weapon abides by. If no attempt to control is made, and the fire button is held, the weapon moves in a somewhat predictable manner... somewhat. The M4X, moreso than the AR, will attempt to implement horizontal recoil, kicking you sideways off of your target rather than straight up. The recoil pattern for the M4X is also kind of odd, something like a half circle, followed by a kick to the left.
X---\
./
. - Start firing here
X - Run out of ammo here
It's not extremely exaggerated, it's almost like a counter clockwise spiral, but it's enough that I, on more than one occasion, blasted a perfect circle AROUND what I was trying to shoot. My own damn fault for going crazy with the the full auto.
The weapon also has extremely low stopping power. My M4X build, which is admittedly built for low accuracy and recoil, only does 42 damage. 42! While 8 point may not seem like much, it albeit guarantees an extra hit needed to kill even light builds. This may not sound like much, but that horizontal kick can start up any time after that second shot... so you think you're going to put a quick 5 in your target, but you end up only giving away your intent.
The weapon also has a very short range compared to the AR. Almost half the distance before damage starts to drop off, and then it seems to drop off FAST. I've fought ranged battles where I had to put SIXTEEN shots into the other target... SIXTEEN! Needless to say, most targets with nearly any receiver will drop you much quicker than you can drop them at maximum range. The weapon operates at its best within first range increment. Hands down.
If you're using the M4X, take your time and make sure all the rounds meet their mark.