+1 for NOT buying a shitty firearm.
I would look into the differences between the .223 and the .308 (mainly) and maybe even the .30-06... I mean, I guess it comes down to how hard you want that round to hit it's target. .308 is slightly more expensive, heavier, and you can't carry as much on ya - but other than that, the only other contrasting element there is the flight trajectory of the round.
The .223 won't penetrate anything like the .308 would, but it has a nasty tumble inside the target (at certain ranges). It also has a pretty flat trajectory out to 500 yards, I believe - whereas the .308 has more of a curve?
Forget about "flat" shooting. It is irrelevant. The relevant factors are consistency, range, and energy. 308 Win is one of the gold standards of accuracy. It is also good for 1000 yards against personnel. Trust me, you would not want to be hit by one even at that range, or any range for that matter.
The other non-performance related factor to consider is availability. There is a LOT of 308, 223, and 30-06. If things turn truly sour, people with 6.5 SPC rifles will be able to break them out, look at them admiringly, and then put them back. Guns are worth nothing without ammunition. Better to have a .22 with plenty of ammo than a 408 Cheytac with none.
And that is the last thing I will say on this: before buying ANY other rifle, you should get your hands on a .22 lr. Twenty twos have taken more game than any other caliber. You can stock up on 10K rounds for what it would cost you to purchase 100 rounds of .223.
I have an old Stevens Model 34 that I got for $90. I reworked the stock - it now looks similar to a Winslow dangerous game rifle.

It is deadly accurate to about 100 yards and hits plenty hard to perhaps 75. It is all that 95+% of all people will likely ever need. IMO it, and a large supply of ammunition should be the first item on that list of rifles. Once in place, then start in on those longer distance items.
Best wishes to one and all.