AK47 vs. M16 Rifle

By most measurements, they appear nearly identical.
Weapon AK-47 M16
Manufacturer IZhMASh Colt Firearms
Design year 1947 1957
Weight (8.4 lb) (7.9 lb)
Length (34in) (39in)
Caliber 7.62 x 39 mm 5.56 x 45 mm
Rate of fire 900 round/min 800 round/min, cyclic
Effective range (328 yd) (600 yd)

But a huge difference is number of rounds/pound when you are carrying a full battle pack. Run out of ammo, and the marines fix bayonets and charge. It worked in Iraq, but it is much better not to run out of ammo just because the another 50 rounds was too heavy to carry.

A big difference is recoil. Less recoil, more accurate fire is a big justification for a submachine gun. (Sub means pistol caliber.) That is why Swat teams use 9 mm HK's. The M16 allows similar accuracy when firing 3-round bursts or more. And the M16 retains its long range to reach out and touch the bad guys on a desert battlefield.

The AK-47 has always enjoyed a reputation of reliability. It is gas operated, using the gas from the barrel to push a piston attached to the bolt carrier, operating the action. The gas tube is fairly large and is visible above the barrel. The AK-47 is often built with generous tolerances, allowing it to function easily in a dirty environment. It is very simple to disassemble and clean, easily maintainable by "a peasant with a flat rock."
One major factor in terms of reliability lies in the design of the AK-47's magazine feed. The top of the magazine is machined from a single steel billet, making it practically impossible to damage the feed lips causing jams or misfeeds. The M16 (and other NATO mags) are sheet steel pressed, resulting in a relatively fragile feed system. This attention to detail reflects the AK-47's combat-_base_d design; in combat, equipment suffers from hard use and gets damaged.
The M16, though, had reliability issues in its initial deployment, but were quickly fixed in new versions. The direct impingement gas system used by the M16 is similar to normal gas operation but with a few differences. Gas from the barrel is used to cycle the action but lacks the piston, so the gas alone impinges upon the bolt carrier. This design allows residue to be blown into the receiver as well as quickly accumulating carbon build-up within the gas port channel, negatively affecting reliability. The original M16 fared poorly in the humid, dirty environment of the Vietnamese jungle, due to a change in propellant not well tested beforehand. Part of the problem was the M16 was billed as self-cleaning, and cleaning kits were not issued. The infamous reliability problems were due to production errors and a conscious decision on the part of the military to use the more powerful "ball powder" ammunition in the cartridges. While ball powder resulted in a higher muzzle velocity, it created much more residue. The weapon itself was designed to fire cartridges with stick powder. When cartridges using stick powder were introduced, the reliability problems faded away.

US military weapon designers are no dummies. They are way ahead of most AK47 fans. One big reason that many 3rd world armies do not use the M16 is cost. The AK47 is much cheaper. But, several foreign armies use the M16 (or knock offs) if they can afford them.

In private hand there is a potential safety threat because the background check and permit process -- which anyone interested in the weapon must go through with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives -- may not will weed out potential bidders who might have criminal intentions. Even, private sector pre-employment background check can be more thorough that the ATF because private sector checks can cover more categories of information like current phone number, address, address history for 30 years, age, birth dates, household members, relatives, associates, property ownership, lawsuits, marriage, divorce, criminal records check, sex offenders, terrorist watch, bankruptcy, tax liens,