Re: Predators vs. Military
In the first movie, the predator was wounded after the team shot up the jungle. Yes, they fired an amazing number of rounds, but almost all missed.
They were firing 9 mm SMG, 5.56 ball, 7.62 ball, and 40 mm grenades. (Yes, we do not know that they were using standard "ball" ammo, but in that time period, in that area, it is a given.) One or more (probably one) rounds hit the predator, and wounded it.
Based on that, 7.62 AP would definitely penetrate the predator armor, 5.56 AP probably would, and 5.56 and 7.62 "special" AP both definitely would.
It has been mentioned that in the second movie a shotgun didn't penetrate the armor at point blank range. Well, shotguns may have GR8 power, but they have very poor penetration. (Unless you use very special sabot AP ammo, which I do not believe is commercially available.) So military rifles with "special" AP rounds will work.
It has been suggested that predators would just stand off at long range and use their DEW. I don't think so. I don't recall its use in the second movie (I've only seen that one once) but in the first movie the weapon is clearly some kind of "particle" weapon (plasma gun?) that is sub-sonic; it will have a lower effective range than modern rifles.
Finally, if we assume that the predators shown in the first 2 movies are hunters, that does not automatically mean their weapons are not state of the art. Until WWII, human soldiers' personal weapons were not better than hunters' weapons.
Of course the "colonial marines" from Aliens are better armed than modern day infantry.