Before the government screwed things up, we used to buy K22s at gun shows for $200 on average. Occasionally you would find a good 5 screw but most were just good pre Bangor Smiths. I have a M18 and it is a handy and very accurate piece. These older Smiths just yell quality, especially a really old example such as yours. I really think that people don't realize the value in these older pistols: they never wear out and even a well worn K22 will shoot perfectly for another lifetime. Congratulations on a good find.