A lot of the tournaments now use Pocket Radars on a tripod. They are usually pretty accurate if used straight on with the pitcher, but otherwise read slow. In some cases, an anomalous reading shows up though. A kid on my son's team who had been throwing 76-77 on a "slow gun", got a reading in the mid 80's. When he found that out after the game he was super happy, and couldn't wait to tell his pitching coach and friends. I saw the pitch and the subsequent reading. It was a misfire that bounced about 10' from home plate.
That max velo was posted on the tournament game log, and is now on public record, if someone cares to dig enough.