At the time they were one of the better .21 OB tunnels, that one and the one that Ed Hughey produced. The Dumas Hot Shots were junk even back then against the Klampon-Kai.
They came on the scene in RC OB tunnel boat's infancy, the late `70's. Ed's kits were pre-cut, machined I think but I don't know how the Midwest kits came at the time.