So it seems the big thing now, especially as being pushed by NSSF, is the "modern" sporting rifle. It's a euphemism for the AR-15 platform. If that first remark seems disparaging, it's not meant to be - I just detest euphemisms. I don't call a Remington 700 a "modern bolt-action food acquisition device" for a reason. It's a rifle. It kills tasty creatures for my grill and table. 'Nuff said.
So, what's the general consensus on the AR-15-based hunting rifles? Specifically, are they an appropriate tool for killing game? As a varmint gun, you have a wide range of choices in .223 Remington, so for things like coyotes, prairie dogs and gophers they are a perfect platform to reach out and touch someone. Let's call the first category "pest control" - check.
What about larger animals, like antelope, deer and wild pig (under, say, 150lb). Personally, I'm not going to want to take that kind of shot with .223 Remington/5.56 NATO. The wound channels are too small, assuming proper ballistic flight characteristics (i.e. bullet speed matched with barrel twist rate) and the collateral damage to the animal is, in my opinion, questionable for taking them down with a single clean shot. That leaves us with other chamberings for the AR-platform rifles, like 6.8SPC, 6.5 Grendel, 308/7.62x51 (AR-10), maybe .243 Winchester, and whatever else is out there (seems to change weekly). Those rounds are probably better suited for larger game, but then in at least some cases you run into the issue of ammunition availability and cost (6.5, 6.8). So would people be willing to hunt larger game with an AR-platform with a round packing a little more kinetic energy than a .223/5.56 bullet? Let's call this - "larger game" - check.
Finally, you've got your world of big old meat-bearers, like black/brown bear, elk, moose, mule deer and things like that. This is an area in which I have no hunting expertise. Frankly, I'm not willing to pay ludicrous sums of money to go out of state for an elk (yet) and certainly not willing to pay the California Department of Fish and Game ludicrous sums of money for a permit to take one elk at a place like Grizzly Island (assuming you even get drawn for the tag.) So, is this type of hunting a place where the AR-platform rifles just fall down on their face and can't keep up with the big magnum boys? We'll call this "big game" - check.
Then there is the argument about using a bolt-action rifle vs. a semi-automatic rifle for hunting. Some folks apparently think that using a semi-auto rifle is not 'sporting'. The figure in the magazine capacity of the respective rifles. 3+1 or 4+1 for a bolt gun, and anywhere from 5 to 40 rounds in a semi-auto (i.e. 30-40 in the AR, more if you own and want to hump around beta mag). Personally, I don't find a semi-auto in and of itself to be non-sporting in terms of pursuing game. You should shoot what you like, what you're comfortable with and what will get the job done. I do wonder, though, if knowing you've got the ability to get 5 or 6 rounds off in the time it would take a bolt gun to get 2-3 rounds off on a good day, engenders taking shots less certain of being clean. I have no opinion either way, just a question. Obviously an ethical hunter wouldn't do such a thing, but not every hunter is ethical. Let's call this "hunting ethic" - check.
Finally, I'm going to ponder reliability. The AR-15 platform is generally reliable, given proper feeding and care. However, I've been party to a few AR-15 platform stoppages that absolutely baffled the living daylights out of me (other people's rifles, not mine.) I know for a fact in several of the cases that the rifles were shooting proper ammunition (factory stuff) and were properly built and maintained. A few malfunctions required near total disassembly of the rifle to unwedge various pins and springs, and that was just so we could safely unload and inspect the rifle.
On the other hand, a bolt-action is inherently a simpler type of action. No gas tubes, no buffers, fewer springs and pins and overall a simpler mechanism to operate, inspect and maintain. That's not to say a bolt-action won't fail - I've had that happen to me too. Firing pins break, extractor claws chip, triggers go out of tune, grit gets into the action and jams up the bolt and so on and so forth. This last one is "reliability" - check.
So, in terms of:
how does an AR-based sporting rifle fare? Hopefully folks have some interesting opinions.