I don't believe I specifically indicated that the 223 max range is 300yd, and I'm not sure how my apparent lack of experience should preclude me from spouting vile heresy on a forum. I will however note that beyond 300 yd, it is an inherently handicapping cartridge, even with a berger heavy. If your rules indicate you may only use a 223/ 80.5gr or 308/155 gr, then you aren't in bad shape as the two choices are close to ballistically identical. If you aren't restrained by such rules, there are much better options. Yes, 223 will teach you how to read wind. Yes, it will drop like a 155 308 bullet at range. Absolutely, you can shoot it at extreme ranges accurately. But, in order to shoot at any extended range, and do it well, you begin to encroach the cost bracket of higher performance cartridges, in which case you might as well pick one of those better performers because either way you're going to be paying for it. For an extra ten to fifteen cents per shot compared to 223 you can now have a cartridge with remarkably better performance and usability.