Interesting that it has a red ramp front sight instead of a black patridge. I would guess that's an owner-preference swap-out from later in its life, but it is possible it was special ordered from the factory like that. The ramp sights usually went on the shorter barrel guns like the Combat Masterpiece (four inch instead of six). I can't remember when the red insert became available. The earlier combat-style ramp sights were just unhighlighted steel.
Good looking gun. I have a couple of five-screw K-38s, and I am sure they are intrinsically capable of better accuracy than I have achieved with them so far.
Without a top sideplate screw, your gun is considered a four-screw model; that engineering change dates to 1956. It sounds like your gun is not model marked in the yoke (MOD 14), so that makes it a K-38 with a fairly uncommon configuration -- a four screw gun without a stamped model designation. Model stamping was authorized and initiated in 1957, but non-model marked guns were still being taken out of inventory and shipped into 1958 (and even later for some low-demand models).