I just built a new AR. I put a Hart 26" barrel on it. Chronographed it the other day and to my surprise I was only getting 3175 fps. I am shooting 50 gr v-max, 26.5 gr of varget. Just guessing I thought that I should at least get 3450-3500 fps with that load. Any ideas?

Try another powder. Varget is relatively slow burning compared to the ball powders. It is suited for the heavier (62-77gr) bullets. I have had good luck with H335 with the lighter bullets. I use 27gr with a 40gr Vmax. W748 is the military equivalent. Go over to the reloading section for more advice.

By far my favorite powder for the 50-53 gr. range bullets is Benchmark. Burns very clean, great velocity, meters good if you are using a throw, and it's supposed to be temp insensitive. My second fav is AA2015. Varget is a good powder, but too slow for 50 gr. bullets. I get 3515 fps. out of a 26" 1x12 twist Rem 700 using 50gr. V-max's and Benchmark. That doesn't mean you will, all chamber/barrel/load combos are different, but I bet you'll be happy.