The M16 is more accurate than an AK47. The M16 also went to a lot of effort to have its recoil forces straight back against the shooter’s shoulder, so you can keep it on-target much more easily when firing burst or full auto. The AK47 is a lot harder to keep on-target on full auto.
The M16 fires a lighter round. Whether this is a plus or a minus depends on your point of view. From a soldier’s point of view, the M16 doesn’t hit as hard, and will be stopped by walls or thick brush that an AK47 can shoot through. From an army’s point of view, the M16’s ammo is “good enough”, and being smaller and lighter means that the soldier can carry much more of it. Plus for the same number of ammo trucks, cargo planes, etc. you can move a lot more of the M16’s ammo than the AK’s. The lighter round was controversial when it first came out, but in the end the Soviets also switched to a lighter round with the AK74.
The M16’s greater accuracy comes at a cost, and you can argue that this extra cost is just wasted money. When you hire a bunch of soldiers, the more time you spend training them, the less time they have available during their tour for actual soldiering. Your basic front-line grunts aren’t expected to all be expert marksmen. They are basically expected to be accurate out to somewhere between 100 and 200 yards. The AK47, despite being less accurate, meets this spec easily. In every group of grunts, you’ll have some that were hunters or liked to target shoot, or maybe they are just a bit more talented than the rest. These become your designated marksmen. This is not a sniper. A marksman serves with the grunts, so he’s just another guy in the field. But he is given a bit more training, and he’s expected to be accurate out to a much greater distance, typically 600 to 800 yards or so. Snipers, by comparison, typically work in 2 man groups, and unlike marksmen, they aren’t with the grunts. They are also given different weapons, and different training. Marksmen need to go after multiple targets quickly at a distance. Snipers are often going after single targets and remain concealed.
Since the marksman needs better range, he’s not given an M16 or an AK47, he’s given an M14 or an SVD. So there’s really no need for an M16 or an AK47 to be accurate beyond a couple hundred yards. This makes a fairly valid argument that the U.S. is wasting its money on the better accuracy of the M16.
The extra accuracy of the M16 not only costs more to produce, but it also means that the rifle is much more of a precision machine. One great benefit of the AK47 is that it is intentionally made out of loose-fitting parts so that you can easily produce one on much cheaper and simpler machine tools (it is possible to make a very tight-fitting, highly accurate AK, but that’s not what it was designed for). You can drag an AK through the mud and not bother to clean it for years on end and it will probably still shoot. Do the same thing to an M16 and it will fail to cycle fairly quickly.
The M16 has a bad reputation because of a lot of early problems that it had in Vietnam. Those problems were fixed (and that stupid forward assist was added), but a lot of folks still think the M16 is an unreliable piece of crap even though that’s no longer true. The rifle is actually pretty decent these days. The M16’s bad reputation is slowly getting better, especially with the popularity of the fairly similar AR-15 type weapons.
So what does all of this mean to the Taliban?
Well, first of all, we’re not comparing new AK47s to M16s. Their choice is to use brand-spanking new M16s or keep using 50 year old AK47s that have had a very hard life. A lot of them are going to choose the newer M16 since it will likely be more reliable even given the AK47’s better design with respect to dirt and mud.
Ammo is going to make a big difference in the choice as well. We left a lot of ammo behind as well, so how that gets divided up will determine who gets M16s and who sticks with their AK47s.
In that part of the world, there is a common misunderstanding of the purpose of the M16’s forward assist. I personally have a pretty low opinion of the forward assist. If you are having a feed problem, the last thing you want to do is just say screw it and use the forward assist to slam the round into the chamber. What you really want to do is stop and fix the feed issue before you make things worse. The weird thing is that many people in that part of the world think the forward assist is the “sniper button”. They know that bolt-action rifles are more accurate than auto and semi-auto weapons, so they think that firing the M16 while holding down the forward assist makes the rifle more accurate, since it stops the action from cycling. In reality, all you are doing is unnecessarily stressing several parts of the weapon, and not actually making it more accurate. Some members of the Taliban are going to prefer the M16 though because it has this “sniper button” that they think makes it more accurate.