I owned one of the first KS-5s, in fact one of the 35 or 36 that had scroll engraved receivers called Scroll Arabesque grade. It had a fixed choke but tubes were available. If I have my numbers right, they listed for $5,800 and since a K-80 with one barrel wasn't "that much" more at around $7,000, they didn't sell well so Krieghoff was closing them out at the 1986 Grand for $3,600, only about $800 more than a standard grade KS-5. When I passed to to my son, I bought a KS-5 Special and later one of the first KX-5s to enter the country. All three were great shooters and the cocking via the top lever was never an issue for either of us. It did help to place your fingers on the wood alongside the lever and "squeeze" with your fingers and thumb.
Yes, the "KS-5" name did originate in "Krieghoff Single" and either the year (1985) or the number of moving parts, which was five or six with a release trigger. Interestingly, there were two screws in the trigger, one that adjusted the pull trigger sear and one for the release sear if the gun was so equipped. Krieghoff International later drilled the Allen screw heads out of the screws for liability reasons when the guns were returned to Ottsville for servicing but I could change my first KS-5 from pull to release and back again in seconds - about one full turn one way on one screw and a full turn in the opposite direction on the other screw (or something like that - it's been 30+ years).
My only complaint with either gun was the plain wood they came with. My KX-5 especially looked like oak furniture and I was fitted and picked out AAAA Exhibition-grade English Walnut blanks for a Wenig stock at the last Grand at Vandalia (it was almost as much as the gun cost!). It was a gorgeous gun and I believe someone in the western part of the country now owns it.
Ed