i finally figured out the usage for this weapon. at first, the machine gun/rifle confused me because i couldn't figure out why on earth it had a scope on it, since every time i would shoot a enemy, it would hit, but not down him with one shot to the body...like the sniper rifle or the anti-armor rifle.plus, once you fire, it had so much recoil, you couldn't keep firing it using the scope. Then i figured it out. 1)you have to be between 100-150 meters from your target. 2)you have to be squatting/stealth/strafe kneeling. 3)it has to be a head shot. and only just one shot...tap once the R1 button. Now....you can take out an enemy with one single shot...just like a sniper rifle. the usage is good for taking out a horde of enemy troops from far away without worrying about running out of bullets.
*note* if you try to hit an enemy by aiming for a head shot...but you aren't kneeling first or below 100 meters,...even if you have the enemy's head clearly between your crosshairs, you'll still miss. The shot does NOT go where you are aiming.
lastly, yes...there is a AR MAX code out there that unlocks all air strikes, supply drops, vehicles AND gives you 1 billion dollars to use on your air strikes, supplies, and vehicles. makes the game easier, but 1000X more fun!!!