There's a track marked on the map that runs north from the road that skirts the south of Slievecorragh. I headed along here past the 1st old farm building until I reached the 2nd ruined farmstead. The bullaun is in the marshy field to the west of this. I spent about 20 minutes scouring this field in increasing frustration and headed down to the rath for a look.
The rath is fascinating, with the deepest fosse I've yet seen on one of these. It's easy to explore at this time of year but would be impossible in the summer months. The inventory says that there's no sign of an entrance, but they visited in August and I saw a clear entrance in the north-east quadrant.
Heading back into the bullaun field I noticed a cluster of boulders beside a massive gorse bush. The bullaun is here, almost flush with the ground. It's a little over a metre squared and the basin is one of the smallest I've seen, placed centrally in the stone. The sides are sheer, carved directly down into the flat-topped boulder to a depth of about 15 cms.
"A scealp is a cleft or chasm; the word is much used among the English-speaking peasantry of the south, who call a piece of anything cut off by a knife or hatchet, a skelp." The Origin and History of Irish Name of Places P.W. Joyce