Nikko Stirling make some, available at Optics Warehouse.
Cheap and not the best quality in the world but all I have found that will fit (tight fit, put on a radiator for a few mins and its easier)
Use the drop down menu to select the 60mm size.
Daystate Mk4 iS ST (Huggett shroud & Mod .20) Lightstream 4.5-14x44 FFP
Daystate Grand Panther (Grand Prix stock, .177) Nikko Stirling Diamond 10-50x60
Daystate Panther (Gary Cane custom stock, .177) Sightron SIII 10-50x60