Hello Candyman
I agree with Forum Poster David Wilson on this. Your gun is indeed a Pre-17 Four screw Variation. I have one in the safe just like it, but mine has the Earlier style Fish Hook up-swept style Speed Hammer on it, where as your's has a semi Target style later version hammer. Mine has serial number K-26831X & it was shipped out of the Factory in July 1956 to The Shapleigh Hardware Company in St. Louis, MO. as shown on the bottom of the box as they evidently logged the S&W's in as they showed up there from the factory, and dated the boxes that they inventoried. The Shapleigh hardware company was a Huge S&W Wholesale stocking dealer back then, & Oddly enough, This one sat 21 Months on their shelf before it sold by evidence of the Original sales reciept shown with it. The Four screw variation Pre Model stamped 17's "Are Very, very Scarse" compared to other the other early variation's of the model 17, and a Lot tougher to find than any the other Variations. We Do know that They ceased using the upper side plate screw sometime in the late 1955 time span and started stamping the Model Number 17's in 1957 as MOD. 17 in the crane area, therefore a Pre-Model stamped 17 in Four screw configuration was only seen about a Year or less of life span. Here is mine it came out of the Astute David Carroll collection. It came to me Unfired with everything it left the factory with in July 1956 as shown below. If you Pull The Magna stock's they should have the guns serial number stamped into the inside of the right grip panel. To do so, a word of caution on this Procedure first here as these hand fitted stocks tend to fit Very tightly and to avoid any damage to them, Never attempt to Pry them off the frame of the Gun simply loosen the grip attachment screw and push off the opposite grip Panel by applying pressure to the grip screw head with a good fitting high quality screwdriver. If it were me, I would Hang Onto that Very Hard to find Variation Pre-17 K-22 as I feel someday the demand will be as strong for these Pre-17's in the Four screw form as it is for other low production, short window span K-22's. Here is everything your Pre-17 would have come with, and I wish mine only cost me what you paid for yours but I have No Regret's as mine is new in Box and complete, and will remain that way as I have Plenty of other K-22's to enjoy without de-flowering this one's Virginity.... Regards, Hammerdown