I just got one of these SIII 45x45's a couple of weeks ago. I'm happy with it. Excellent ED glass, and the 1/10 MOA dot & turret adjustments should be great for 600-yd. shooting. I'm a big Sightron fan. If you decide on one of these, be sure to check with Lance at Buchann Accuracy for the best possible price. He saved me a bundle on mine.I have the Sightron 45x and really like it. Glass is a definite upgrade over my SIII models