Just to the southwest of the summit (perhaps 500 metres, maybe less) is the small Rifugio Don Zio. This can be a good place to stop for a drink or to rest, but beware: we found out that (in July, anyway), that it is only open on weekends! Plan accordingly.
From the rifugio, head south down a gravelled road (which is also signed as path 411) towards the junction 'Le Quadre'. There road passed through beautiful open grassland as you descend this portion. At the 'Le Quadre' junction', you've re-entered the forest. Turn left onto trail 408 towards 'Acqua del Duson'. Easy hiking down a gently descending trail brings you to a short side trail left to the 'Acqua del Duson', which is a small spring.
Continuing straight on 408, you shortly arrive at another junction - sort of a 'Y' junction. Head left, staying on trail #408. About 270m beyond this junction, you'll come to another junction, this one a T-junction. The straight-ahead-on-the-flat route is the continuation of 408. The route left immediately descends down through forest on an extremely steep trail. This is the descent route. The trail is even protected by a wire, and really, you could call it a very low-grade ferrata.
The trail descends extremely steeply through the forest, mostly protected with the wire, descending about 250 metres (800 feet) in only about 200 horizontal metres. The end of the really steep stuff is marked by an old, decrepit ladder. Below this, the trail is merely only very steep, and the wire ends.
The path more-or-less heads down the fall line of the slope, through the forest, until it intersects an old forest road. The trail crosses over the road and continues straight down the slope, crossing and re-crossing the switchbacking forest road several times. There is one spot in the guidebook that describes turning left onto the road at a forest road gate, but that seemed to be incorrect information - the best choice was to continue straight across the road on the trail. Eventually the trail reaches a lower stretch of the forest road and does not continue across. Turn left and follow the forest road at this point, and it leads back into the town of Pietramurata. There is a small open area just before where the forest road becomes paved and meets the main road. If you have two cars, you can park the second car here and be finished with the route at this point. Otherwise, you have to walk down the main road for over a kilometre to get back to the start point.
I found the steep descent back to Pietramurata long and tiring. I think that a good alternative, if you have two vehicles, is to find a spot (i.e. a trailhead) on the other side of Monte Casale and take one of the foot trails that descends that side.
Quick Reference Ferrate Route Index
rating from the newer Cicerone Guide by Fletcher and Smith
(**) Difficulty rating from older Cicerone Guide by Hofler/Werner