Condition trumps the markings on pre/post 17 marked 4 screw guns, but looking at the timing, the 5th screw eliminated in '55 and mod marking starting in 57 would not leave a lot of time to make K22's that were 4 screw and unmarked. Esp with current inventory 5 screw frames on hand when the engineering change was made.
4 screw model marked 17's were possibly made 57 thru 61. 4 yrs versus 2 yrs, and you have the 17 and 17-1's both in this era, so there are two versions to consider.
I have to go back to condition to base a choice on.
Charlie