Forget Olympic. There are better choices. Like RRA and Bushmaster. They cost a little bit more than $700, but it is definitely worth it.
Don't worry about the "lifetime warranty", that is more marketing than anything else. The advantage of a well known brand name is not warranty, but rather resale value.
The typical things that break or go wrong with an AR are far, far cheaper to buy locally and repair/replace yourself than it is to pay for insured UPS shipping + wait time to send it to the manufacturer.
One of the reasons I love the AR, is that with $60 in tools, I can fully gunsmith the entire rifle. Now, for small parts repair or replacement, you don't need all of that. It's one of those guns that doesn't really need to be sent back to the manufacturer unless there is something severely wrong with it, like canted gas block that you cannot fix yourself or something is out of spec, or something is warped/cracked.
What do you mean by shoot accurately? Do you plan on scoping the rifle and shooting from a bench or bipod to get small groups? If so, barrel selection will require attention. If you just mean accurate in general, the AR in any configuration is accurate enough for 300 yards, and I highly recommend getting a barrel in some type of GI-profile (lighter under handguards or lightweight in general).
Also the RRA comes with a very nice 2-stage trigger that will make your 300 yard range shooting so, so, so much more enjoyable and accurate.
