First off, park at 44° 38.199N, 121° 08.130W (East end trailhead). This is a public paved parking area. Follow what looks like a trail (paved), and that will take you across a paved road, and picks up on the other side of the road a hundred or so feet west.
Then continue a couple miles (yes it is a hike) to 44° 38.752N, 121° 10.049W, the coordinates for the actual cache. You are walking along the abandoned railroad bed of the Oregon Trunk Railway, one of two tracks built simultaneously into Central Oregon from the Dalles, in 1911. These tracks extended under the current railroad trestle which is a backdrop to Madras, then turned south to a depot in the general area of Deschutes Valley Water District building, then south to Metolius. Not much left of the railroad (in this canyon, anyway) except the grade, and a few old ties here and there strewn to the side. This trail extends from the West end of Madras all the way to the outlet of Willow Creek above Lake Simtustus, and we recommend the total hike to anyone who enjoys spectacular rock formations, mountain views and river settings, in a very isolated canyon. Don't forget your camera!
Good luck!
PLEASE NOTE: There are coordinates in the cache for a bonus hunt called Oregon Trunk #2 which no longer is active. It's a beautiful spot to visit if you're doing the complete hike, but the ammo box is long gone.