The AR-15's 5.56mm NATO ammunition [1] is designed to be light and portable, and to injure rather than kill. Compare that to, say, the AK-47 and it's 7.62x39 ammunition [2]. The energy of the AR-15 ammo is about 1300J, while that of the AK's is 1500J or more.
7.62x39 is not a NATO round only because it's Russian in origin. It's generally the same is the 5.56 (basically a .223) in that it's a non-expanding bullet typically due to the FMJ (full metal jacket). The light and portable part is mostly due to history - the arms race of more shots equaling more kills, and mobile infantries. Compare that with say the .30-06 or 7.62x54 which are big rounds shot from big, heavy rifles (M1 Garand and Mosin-Nagant, respectively), a holdover from trench warfare.
You can purchase non-NATO 5.56/.223 ammo for hunting, and are typically required to use it when hunting game. The opposite of warfare, it's considered more humane to kill an animal than to injure it.
7.62x39 ... It's generally the same is the 5.56 (basically a .223) in that it's a non-expanding bullet typically due to the FMJ
The fact that they're typically jacketed is where the similarity starts and ends. They are loaded differently, spin at different rates, and so on. But most obviously, 7.62x39 is almost twice the diameter of 5.56.
7.62x39 is probably much more comparable to the .308 Winchester [1] typically used for hunting larger game. According to wikipedia, "the .308 Winchester has become the most popular short-action, big-game hunting cartridge worldwide".
Now, circling back to my original point about the AR-15 (or, really, the 5.56mm cartridge it shoots) being low-power, wikipedia lists the energy of the energy of the .308 bullet at 3600J-3900K, nearly triple the power of the 5.56mm.
So I stand by my claim that the AR-15 is a low-power rifle.
You can purchase non-NATO 5.56/.223 ammo for hunting, and are typically required to use it when hunting game.
This is absolutely false. 5.56mm ammunition is too small for hunting deer, bear, etc. You've got to be a very good shot to take down large animals with something bearing so little energy. That's why hunters tend to use rounds in the .30cal range -- like the .308 I mentioned, and also very commonly the 7.62x39 from the AK, but when hunting it's probably being shot out of an SKS [2]. Wikipedia verifies that "In the early 1990s, the Chinese SKS rapidly became the "poor man's deer rifle" in some Southern areas of the United States".
So there are a variety of larger cartridges used for hunting larger game, generally in the .30cal neighborhood or more, because the 5.56mm/.223 cartridge just doesn't carry enough energy to take down the big animals.
You can purchase non-NATO 5.56/.223 ammo for hunting, and are typically required to use it when hunting game.
I re-read my sentence and it didn't come out quite right. I agree that 5.56/.223 isn't your typical hunting round. What I meant by my sentence is that you can hunt with it but it isn't generally legal to use non-expanding rounds for hunting.
So I stand by my claim that the AR-15 is a low-power rifle.
No need to move from your position, you are correct. It's an instrument of war and not utility.
There are slight ups and downs depending on the size of game but I agree that the .308 is probably the de-facto starting round for big game.
7.62x39 is not a NATO round only because it's Russian in origin. It's generally the same is the 5.56 (basically a .223) in that it's a non-expanding bullet typically due to the FMJ (full metal jacket). The light and portable part is mostly due to history - the arms race of more shots equaling more kills, and mobile infantries. Compare that with say the .30-06 or 7.62x54 which are big rounds shot from big, heavy rifles (M1 Garand and Mosin-Nagant, respectively), a holdover from trench warfare.
You can purchase non-NATO 5.56/.223 ammo for hunting, and are typically required to use it when hunting game. The opposite of warfare, it's considered more humane to kill an animal than to injure it.