Re: Do any of you use a GPS for rangefinding?
A GPS can be used as a range finder but there are certain limitations to them. I did an experiment last summer to test the viability of using it for targets, I took my WAAS enabled etrex out and shot 5 different points about 500 yards apart 10 times, each shot on a single point was 15 minutes apart so that I would negate problems with satellite geometry. All 5 points were also at least 50 yards from any tree, power pole, or object that may induce multipath errors. The next day I borrowed my company's survey grade GPSs and collected data on each point for 2 hours. After the data was collected I averaged all of my etrex points and sent the survey grade measurements for OPUS solutions. After everything was completed, most of the averaged points were within 3 yards of the OPUS solution with 1 point being 10 yards off.
While under ideal conditions, a recreational grade GPS can be reasonably precise, don't put your faith in the "I BELIEVE" button. Most recreational grade GPSs are only good for +/- 15 yards if selective availability is turned off and conditions are ideal. But if you have multipath error, you may be lucky to get withing 40 yards on a single shot. Also if any of the SVs have a timing error, you could be off by over 100 yards.
I think that too many people hit the mark button and take the coordinates to be fact.