You can use your pins or at least one of them and at least one other point to establish the position of your cache. It requires a good compass. At the cache take a reading for at least 2 fixed points. Record the Inverted course as well. Three is better though. Mark the pin really well so you can find it in any weather. To find your cache star at the pin or one of the other fixed points. Follow the Inverted compass reading. Take sightings on the 2 other points as you near the distance. When all three aline with the recorded headings, you are on your spot.