Questionable Results from Ultrasonic

[Cinnamon Toast]

I'm wondering if anyone else has had this problem...,

We've looked into using ultrasonic sensors from maxbotix to go ahead and try distance sensing for aiming. We did some benchmarks under very optimal conditions (hard target surface, no objects to the side to accidentally detect, and so on) and the results aren't stunning. After a very short distance ( 1 - 2 meters), it seems that the distance readings tend to break down. After a couple of meters, it'll return the correct distance half the time and then return something way to short. Has anyone else had this problems with the Ultrasonic sensors? If so, how did you over come it?

-Cinnamon Toast