Nylon 66 - what can I say? - a real classic in rifle design, way ahead of its time, never jam, decent trigger pull and reasonably accurate for that class of rifle (not a precision competition target rifle), nicely balanced and "handy", every CGN should have one, would never part with mine, too bad they are no longer made. My very strong recommendation: get one if at all possible!
Only limitation - not really feasible to use optical sight on the 66.