Bushnell guns are just as accurate, however...
They will not begin to pick up the ball until its further from the pitcher. As a result, they usually read 3 mph "slower" than Jugs/Stalker.
If you have a Bushnell gun that doesn't read fastest/slowest - it's worthless. The gun may randomly only pick up the ball as it nears the plate, then show a reading. This reading will be 6-9 mph off.