So this makes it a little easier.

300 yards is, in terms of a small bore centerfire rifle, mid-range. As such, I think that you're on the right track with the 223 Remington. As for 500 yards shots, if the farthest you have to practice is 300 yards, then the farthest shot you can ethically take is 300 yards, IMO, when shooting at a live animal. As a hunter you owe it to the animal, and other hunters, to take only shots that you are confident are within your ability. Taking pot shots at an animal can easily result in a wounded animal that dies a slow death, and also paints other hunters and hunting in general in a bad light.

You say you want to hunt "small stuff." If you're talking about small game then the 223 is actually going to be a bit overkill, since only a precise head shot will leave much in the way of edible meat, and shooting a 223 up into the air at a squirrel is dangerous. For small game, I'd recommend a 22LR or a shotgun. Now if you're talking about varmints like groundhogs, coyotes or prairie dogs, then the 223 is the ticket.

You didn't really give us a specific budget, but if you make minimum wage you're probably going to be pretty limited unless you plan to save a long time. I don't know if you live with your folks, or if you're on your own, but I'd be inclined either way to say that you might be better off putting your money toward a more productive end, like saving for college or a down payment for a house. I can't tell you how to spend your money, but I've made a lot of mistakes with money in the past and many still haunt me to this day. The issue is that you want a heavy barrel "sniper style" rifle, implying that you want a super-accurate rifle with bells and whistles. The problem is that these don't come cheap. Probably the least expensive rifle that would meet these criteria would be the Savage 10FP. It's a plain jane, entry level "tacti-cool" rifle, with an MSRP of $719. The street price will probably be in the low to mid $600's.

The other thing to consider is that the rifle will need a scope. Most folks make the mistake of spending 90% of their budget on the rifle, and then buy the scope as an afterthought. If you are serious about "long range" precision shooting, then good glass is not an option. Since you want the whole "sniper" experience, you're probably going to want a scope with an adjustable objective, target turrets and probably a mil-dot reticle. Scopes with these features, that are also offer accurate, repeatable turret adjustments, start in the $300-400 range and go up in price (WAY up, in many cases) from there. Don't forget the top end tactical rings and picatinny rail bases that a true "sniper rifle" should wear (another $150-200). And if you don't have a reloading setup, you're looking at, bare bones, $150 including dies.

I'm not trying to dissuade you, honest to God. I just don't really think that you understand what you're looking at. A decent deer rifle is a whole different animal from a long range tactical rifle, and if you want the cool toys you have to pay to play. If you're as young as I think you are, I'd say forget the wiz-bang tacti-cool rifle for now and save your earnings for college. If college isn't in your future, then put that money toward a home and establishing yourself first. The rifle will wait for you.

OR, if you want to forgo the wanna-be tactical rifle, you could enlist in the United States Marine Corps as an 0311 (infantry rifleman), then work your way toward becoming a Marine Corps Scout/Sniper. Then you get to play with the real deal, on Uncle Sam's dime. Of course, with STA, there's no guarantee you'll make the indoc, and will wind up just being a normal grunt, but that's the risk you take.

Mike