The B7027 a loop off the A714 through Penninghame Forest. The road was originally unclassified but gained its number in 1932. There is no obvious reason why the road is classified as it serves no places of any size.
We turn off the A714 by the church in Challoch and head almost southwards through the village before bearing sharply left. Maps show a secondary road, now closed to traffic, cutting off the corner; this is the original line of the A714. Our road heads west, then northwest, having already lost its centre line, although this does return from time to time. It becomes more winding as it enters the forest. A couple of lochs are soon visible to the left. After going through a clearing a road bears off left signposted to a hotel; it does continue on to Glenluce and the A75 but that's some way away.
The road continues northwest across land that is either barren or forested and presently crosses a burn to enter Knowe. This is the largest place on the road and so presumably the raison d'être for the B7027 but it only consists of a couple of buildings. There's more of the same terrain on the far side, with the road running northwards for about a mile before bearing round to the left. Loch Dornal is then visible to the right before we skirt the shore of Loch Maberry.
We continue northwest along a winding road through forest and bog, barely wider than single track in places. We pass Loch Nahinie and presently leave the forest, returning to open fields. The road now follows the valley of the Duisk River downstream, with the A714 out of sight on the other side of the valley. We now reach Barhill and end on that road, with the village centre to the left. The A-road has taken more-or-less the same distance to get here as we have but along a straighter, S2 route.