I think there are some areas with awesome genetics for thirds.....but they do seem to be weak more often than other points from my observations.

Here's a 275" (I believe....it has been a while) western Wyoming bull with good (albeit, uneven) thirds. I have to wonder what they would have looked like if he were a few years older...
[Linked Image from i.imgur.com]


Back to the OP....here's a pic of a bunch of what I consider "good" bulls for a fairly experienced hunter to get into on a general season/public land hunt. The 2 biggest ones near the center are well south of 300" I believe.
[Linked Image from i.imgur.com]

Another view of the big bull in the post I made on this thread earlier. This is a top tier bull IMO but isn't much more than 350" I wouldn't think. The do get bigger even on public land open hunts but they're not common and are incredibly tough to kill. I sure as hell have never killed one close to this size. They need age, genetics and nutrition. I am convinced folks that consistently kill bulls like him often put 10X the scouting time in and 20X the overall effort of the average experienced elk hunter.
[Linked Image from i.imgur.com]