I too have the Magellan GPS 315, and I think that the error margin can vary significantly depending on how many sat's it is averaging from. I can sit in my house and have the distance be anywheres from 2-30 feet off, however on my first Cache Hunt, which was today, I was darn near standing on it when it said I was there. When ya find the first one, You will be hooked, I was. I have about 10 more I am wanting to do tomorrow. (: Just keep it up, and you will feel the rewards of finding it. Good luck to you.
Allen
