The Iron Spring Trail is located is southeast Montana, in Custer Gallatin National Forest. This place is extremely remote and doesn’t get much credit for its dozens of miles of trail. The hills in this part of the state are just high enough to receive more rain than the surrounding grasslands, and as a result have some beautiful pine forests.
The closest town is Ekalaka. The trailhead is southeast of town off Snow Creek Rd (Forest Road 3117) The road is a bit rough but was passible in my Corolla. There is an unlocked gate that you are allowed to go through (I asked), just close it after you pass so the cows don’t get out.
The loop itself is about 8.7 miles with 600 feet of gain. It has a couple miles of forest road and several miles of rolling double track trail that doesn’t receive much use. You will likely have the place to yourself, besides cows and pronghorn. There is a small stream about halfway through and great views from the ridge on the west side of the loop.