At the CMP Eastern Games on May 2-3, 15-year old Sam Payne fired the first ever 600 score. Even more impressive, he did it with 50 Xs. I understand he used a 10/22 based rifle. This is an amazing level of skill. Remember, CMP has a minimum trigger weight of 3lbs.
Here‘s a photo of the winners at the event.
(Hat tip: Areg on Rimfire Central)