To add to my last post. Way back in 1980 when Mt St Helens blew its top and all that abrasive ash. Madsens solid a record ammount of Stihl chain for years after in the cleanup.
They sold that chain in the miles

plus alot of other Stihl products.
So it's easy to see Sam and his dad Ralph had easy pickings to get that 10 cube 090 P/C.