[abrockhoff]

.. because of your phrasing im not sure if your talking about shooting distance or the distance your robot travels in autonomous mode.

If I'm correct in thinking that your talking about driving distance in autonomous mode, there are quite a few options to find the distance your traveling, the first is encoders, which you say your having trouble with.

You can also try to use timer interrupts, but if your having trboule with that, you can just count program loops. Each loop is 26 milliseconds, so depending on you robots speed you can estimate the loop count you need to travel a certain distance, and then jsut test your autonomous mode to perfect it.