Guns in general: You get what you pay for. Sometimes you get a gem, sometimes a lemon. If you can, try before you buy. You didn't mention budget, so some of this might be unreasonable.

Any manufactuer names or model numbers I mention are individuals or companies I have no financial interest in, nor am I associated in any way with, other than as a satisfied customer in certain cases.

Every gun person has opinions, and some have knowledge. Here's some of mine. It is up to you figure out where or if it fits in your world.

I've know little 5'2" females shoot 44 magnum handguns and 375 medium bore rifles just fine, and 6'2" big framed men gun shy with a 12 gauge. I submit a good shooter needs to shoot more than 3 rounds the weekend before hunting season. 300 over a couple month span, maybe. Learning the proper way to hold a weapon, and how to properly control the recoil goes a long way to what an individual can tolerate. With a hand bedded action and free floating barrel, most rifles shoot better than the person behind them can hold.

Here's something you might have never considered: snares might be more effective that any firearm, pound for pound. Legal or not, in a real survival situation, I'd take snares over a firearm. It's an effective force multiplier. websearch buckshot snares for pre-made ones.

The distances I discuss below are what I personally would feel comfortable taking a deer sized animal at, based upon my knowledge of ballistics, the un-customised rifle models or shotguns I have used in those calibers, and factory ammunition.
In some cases I may know enough about a load to be able to 'lob' a bullet because I may have shot hundreds of rounds of that particular load to know how it will perform in MY rifle.

Your results will vary.

Shot placement is more important at normal hunting ranges (under 500 yards) than bullet weight, velocity, or anything else. If you hit the target and penetrate into the heart, brain, spine, even with a non-expanding solid, it's down. Lung shots often entail tracking the animal for awhile.

Having said that, are you in the market for an off the shelf weapon, or a customized one ?

Can you legally use a rifle in your state for hunting (whatever ?)

A 12 gauge has a lot going for it, close in. With a slug barrel and scope, maybe 175 yards max. change the barrel and its good for birds. 12 gauge is kind of a universal weapon, ammo is inexpensive compared to rifle ammo, in a survival situation there are even flares available. Knoxx Compstock goes a long way on recoil reduction. Many manufacturers out there. I recommend a pump over anything else.
bird or slug barrels are relatively cheap and easy to interchange.

if you can use a rifle,
reasonable odds are it will see a lot more day hunting trips than expedition hunting. Shaving weight off a rifle increases the price exponentially both from a materials and manufacturing point of view, and a decreasing market share point of view.

I'm not going to discuss the ethics of taking game at long distances, if you, the shooter has not had enough experience firing at the distance the game is at, don't send that round.

when you properly fit a stock, glass bed the action, free float the barrel, you increase the distance the rifle is theoretically accurate at by hopefully mitigating stressors on the barrel, and the human behind it.

Action design:
Leverguns are not possible to really freefloat the barrel or bed the action, therefore they may have some accuracy problems at long distances due to barrel harmonics. Changing wood to Kevlar helps.
Boltguns can have the actions bedded and barrel freefloated.
Both can usually have muzzlebrakes added, and the stock properly fit and a good recoil pad added. There are two common bolt gun designs out there, the mauser type controlled round feed, and the remington push feed. both are good. If you were hunting dangerous game, the mauser type is preferred by most guides/PH's who don't use a double rifle. Most american sniper rifles use
actions based upon the Remington action to some degree.

Cartridges:
243 Win is a classic eastern whitetail cartridge. Good out to about 450 yards if the person can hold it.
It's never been a military cartridge, so it can travel to places where civilian posession of military cartridges are banned (africa, anyone?) Doesn't kick too bad. disadvantages, ammo is expensive, and barrel life is short. I wouldn't hunt medium skinned game with it. Deer, antelope OK, elk or bigger, No.

308/7.62x51 NATO, militaries have and continue to use this cartridge, so there are some countries you cannot take it hunting. Advantages include a large selection of factory loaded ammo, from 55 grain sabots to 220 grain thumpers, with 155 grain and 168 grain being 'standard' and 173 being typical 'match' loadings. Bullet selection is important, and everything from varmints to brown bear has been killed with a 308. Surplus ammunition is available. Nothing makes me warm and fuzzy like a sealed case, just in case. Reloading components are easy to obtain. Recoil is manageable, but: restocking the action to one that fits correctly, addition of a good recoil pad, and adding a muzzlebrake goes a long way to adapting something to cover both intentions. Some mass manufacturers sell them with a muzzlebrake, bedding the action and freefloating the barrel gets the most bang for the buck if you think you're going for a long shot.
Very few cartridges are as versitile as a 308, either. The Palma matches are shot at 800,900,1000 yards with the 308 cartridge and open sights. For an off the shelf one that can be rapidly adapted to an individual shooter, look at Tikka. Some models have a spacer adjustable stock, and have a threaded muzzle for a muzzle brake.

7-08 is an attempt to get more velocity out of a 308 by going to a smaller bullet, moving faster, with higher B.C. bullets at the same mass. It's a semi-wildcat cartridge, and regardless of how many manufacturers offer a chambering, it's still not likely to ever be available at a resonable price in bulk compared to a 308. I do not see the slight advantage of velocity and B.C. outweighing the advantages of the versatility of a 30 caliber tube. I often refer such former wildcats as a solution in search of a problem. very few were more sucessful than the parent cartridge. that said, here's a few notable exceptions.
30-03/30-06 I think #1 in number of US manufactured rifles chambered until the 5.56mm overtook it somewhere in the 1980s ?
22-250 savage, 220 russian/22ppc,6mmPPC, 6.5x284 winchester. used for varmint, benchrest, and long distance, respectively.

With all due respect to benjamin, in his post, I do not agree with a choice of a 7-08. It has a lot of negatives, and the positives it does have can be satisfied by relatively inexpensive modifications to rifles with much better capabilities and ammo availability.

30-06, parent case of many, many other cartridges. Still sometimes considered a military cartridge, sometimes not. Comparable to 7.62x54, 303 british.
Classic deer cartridge, enough to kill anything in north america out to 500 yards short of moose or bear, with heavy loads, those are harvestable at shorter ranges as well. It's kind of fell off the wayside with the gunrag hyped ubersuperduper mags of late. recommend a good brake, bedding the action and freefloating the barrel. done right, it's like a 243 in recoil.
ammo is readily available and surplus can be found for practice.

30-30, legacy of a bygone era, with a thin metal buttplate, mine kicks like a mule. Replace the wood and metal with kevlar and a recoil pad, easy to shoot. Not good beyond about 300 yards, and I hesitate beyond 200. beware of top ejectors and scope use.

45-70, another legacy. but.. with good semi-factory loads, and a muzzlebraked gun..no worse than a 308, and will take anything in the world with proper loads. examine the Marlin 1895 guide gun. reach out to maybe 300 on non dangerous game.
commonly seen where there be bears about.

compact takedown 45-70 levergun: look up Jim West, Wild West Guns in Anchorage, Alaska. called the Co-pilot, for a very good reason. He also does very lightweight expedition rifles.

Levergun with pointy bullets. Winchester 1895 has been
chambered in 7.62x54R,303 british, 30-06,30-40, and 405win.
here's a levergun that you can shoot pointy bullets in, as it doesn't have a tubular magazine. 405 has taken every big game animal on earth. doesn't kick awfully bad in 405. 350 yard gun in 405, longer on 30-06.
You can find them available in take down, and scope mounts are available. One of those with a good brake on it might be a good choice for an all around levergun, particularly in 30-06. Hang a good 3-9x scope on it (Sightron, on the low end, Nightforce on the high end) and go hunting.

That being said, if you're not in the market for a high end gun, a remington 700 from wal mart isn't a bad choice if you keep it under 300 yards in a 243 or 308 chambering. I would however, go with a good scope. Sightron is a good one for the money.
avoid cheap scopes. period.
A Marlin 1895 in 30-30 or the guide gun in 45-70 with the brake are also good choices. Mossberg 500 slug gun, I'd put a knoxx compstock on it before firing heavy slug loads.

for some drool fuel, at the high end, Ed brown, wild west guns ultralightweight expedition rifles,Or WWG co pilot in 457 ww magnum. Take down bolt gun, HS precision. Then price a nightforce scope.

whatever you get, shoot it enough with your chosen hunting ammunition so you know how it performs at your hunting distances.

I carry salt, pepper, tobasco, a firesteel, some snares, and an early Fairchild/Armalite AR-7 with a box of 22 stingers in my day pack. In the unlikely event I find myself in a surivial situation I think I might eat better, longer that way. My hunting rifle chambering is always sized to take care of the biggest problem animal I might encounter, and it depends on where I'm going, what I'm hunting, and how far I plan on walking.

I am in no way advocating snaring (or poaching, hunting out of season, and so on) as a way to procure game animals for anything other than a genuine survival situation.

Another fan of the Ar-7. How nice to meet you. This would be my first choice in a survival situation, most likely used as a single shot, although I do have extra magazines.

My centerfire rifle is a relatively lightweight carbine (Rem 600) in 6mm Rem caliber - a fairly obscure cartridge very similar to the 243. That situation doesn't bother me - I handload.

I would advocate that practice for anyone serious about using their firearm in adverse circumstances. It isn't that hard; our grandparents handloaded around a campfire, at least when melting lead for bullets. Simple hand tools are all you really need. I find handloading almost as much fun as shooting.

The American military has two projects to produce rifles using caseless and polymer-cased ammo and they are supposed to be making good progress with the guns becoming available this year. Ammo that's half the weight would be very useful in a survival situation.
The Sock

hikermor: The real early fairchild ones are better in my opinion than any of the successors..which often only function single shot. and nothing wrong with a 6mm, if you handload..if you don't, then there might be issues with the care and feeding of your 600.

I often take a montana 1999 in 300 win mag (anything other than bear), or a mauser 3000 in 375 H&H (bear, moose, elk)as my primary for most hunting I do, with one of those WWG co-pilots for brush hunting in the swamps(hog).

TheSock: 2 issues with that. 1) civilian ammunition availability, 2) civilian weapon availability. Look at the FN 5.7 mm history for information on that, or the H&K G11 4.73 mm.
It's a great idea, kind of the top prize for weapon developers, short of a hand held plsama gun, but even if it went through testing and trials at aberdeen, ft. benning, and eglin, it might never be manufactured. I assume you mean the AAI LSAT project and the follow on contract..I missed the SHOT show in vegas this year, they might have had something at their booth to play with and to shoot on press day.

If I didn't handload, I think I would stick to military or ex-military calibers. Years ago, I walked into a hardware store in the booming metropolis of Bowie, Arizona. They had every military cartridge from 45-70, 30-40 Krag, on up. Look at how common 223 is now.

Greytruck444.
Yes I am talking about the LSAT project. They say they have made 'tremendous progress' and it might be out this year. But as you point out: it's not a certainty. Hence my 'supposed to' caveat.
A lot of the reason the best equipped forces in the world has a 50 year old rifle design is that the US military keep having trials that don't produce anything better.
Just thought I'd mention it in case everyones rifle is out of date six months from now...
The Sock

TheSock: There are a multitude of reasons the U.S. sticks with the basic M16/AR-15 design, mainly revolving around money. It's a 'cheap' weapon system, and it's firmly entrenched in all branches.
There are several designs that are probably better in some circumstances.
The M14 comes to mind, and it's older than the M16.

If such a weapon was completely proven, and somehow able to be able to be funded for procurement, and if the congress would leave it alone, and so on..
It would be perhaps decades before the US eliminated the M16 platform for all the front line troops and Guard units.

I submit the biggest single problem with the AR isn't the gas system, it's the chambering. It was designed as a weapon for airforce security guards, not for precision targeting at 600 yards + as is seen in Afghanistan. I don't know what an ideal chambering would be, but I don't think the 5.56mm is adequate for the conflicts we are encountering anymore.

And 50 year old design..Remember, we're still flying the B-52, and it was supposed to be obsolete and scrapped 30 years ago. Pilots retiring now realize they're flying a plane their dad or grandfather flew. We still fly the C-130 and KC-135, also in similar situations

FYI, 'Tremendous Progress' might simply mean they fixed the problem of melting propellant, which locked up the weapon during chambering, or the primer tape sliding off. Just remember, everything they release is propaganda to help secure their next round of funding. When I see the procurement contract on the Defense Industry Daily or Defenseworld, then I'll believe them.

I also think if such a weapon was to be successfully developed, it would never be allowed for civilian sale, strictly due to the fact there wouldn't be any shell casings left laying around for evidence, current shellcatchers notwithstanding. That would severely limit the market. If the lawyers keep entrenching themselves further into the military to the point it cripples operational effectiveness and are second guessing every little detail, they wouldn't let such a weapon be deployed. Might hinder prosecuting a soldier doing his or oher job.

I could easily see a heavy material, such as brass, being replaced with some form of high temperature plastic, or nito based smokeless powder replaced with a designer plastic explosive propellant. The hardest thing to eliminate in a caseless design is the primer, and that's the rub.
Only logical thing I can think of there is a disposable single use magazine. but even then, shock sensitivity might play a role.

Actually I was implying no criticism of the M16 at all by '50 year old rifle design'. A lot of people rate the 1911 Colt .45 as the worlds best pistol. And it's a century old. People are certainly still winning competitions with it.
You could hand a modern rifle to a 1916 doughboy and he'd be able to use it with a little examination. Firearms development seems to have reached a peak for the moment.
I'm as sceptical as you are of anything someone needing funding says. But thought it was worth mentioning if you were thinking of equipping yourself.
I'd feel stupid if I'd done the modern equivalent of buying a load of muzzle loaders in 1861 to find the North was massacring the Confederacy with repeaters a few years later.
By the way; they are following two lines of research; caseless and polymer-cased as I said in my first post. So your thoughts on replacing brass with plastic are being pursued. Mechanically it could be identical to an M16; but made of something that didn't need brass to eject a lot of heat along with the casing. Or maybe they'll come up with a plastic that's as good a heat sink. Apologies if this is nonsense. I'm no engineer.

The Sock

I'll simply say I believe there is a reason that a lot of AR-15 manufacturers are pursuing gas piston technology.

If the heat never really gets a chance to flow through the brass casing before it's ejected..or if the casing acts as an insulator, things are good. The heat problem with the existing AR platform is due much more to the gas impingement system heating the bolt and carrier than the cartridge being fired.
This will not mean the barrel itself will not soak heat up, but the chamber is a lot cooler on a piston gun.
Some plastics may be suitable. Whether or not they could be made to fit the existing 5.56mm chamber/throat geometry is a different matter. My gut says probably need much thicker sidewalls, and thicker cartridge web, so it wouldn't work without throating the chamber. Which means likely rebarrelling, as the barrels are chrome lined per mil-spec.
Bottom line, is how much weight is being saved. Is bulk being increased ? End result will probably be a new AR looking weapon
with a different chamber and magazines.

A plastic casing means no reloading. Some of the casing will ablate and change the structure, probably to an unsafe condition.

As an aside, muzzle loaders..look up Harry Melville Pope.

The US Civil War. little known fact. outnumbered, outgunned, outsupplied southerners killed or wounded
30% more union troops than casualties they took during the War of Northern Aggression.
A lot of people might be glad that the south didn't have a lot of Henry, Spencer, and Whitworth rifles. What they did have is people who knew how to shoot and scoot.

For what it's worth, I have a degree in chemical engineering, and I work with certain companies in the firearms industry.

I know I'm so far off topic that I'm going to suggest starting a new thread for future discussions about this.

Yep, the 7-08 isn't the most common of rounds. If economy and availability are a factor, then the 308 would be a far better choice. We were offering a proven upgrade to the 308 in a scouting rifle in terms of down range performance and felt recoil from a common platform. There are certainly myriad other factors to consider, but we agree with the late Mr. Cooper that for a light, effective field rifle, a decent bolt action in 308 or 7-08 is quite desirable, again sighting whichever preference in those conditions are the higher priority for the intended shooter. A 5 lb bolt action rifle shooting a high power centerfire cartridge in this class is certainly not for everyone. For a moderately experienced field shooter, it is of significant interest, as are all the other examples given in this thread for varying shooting situations and conditions, and even shooters.