As far as I have seen, all of the Swiss straight pulls are rough as a cobb and difficult to manipulate compared to the other straight pulls out there; their high quality notwithstanding. I will never understand how anyone could describe them as "smooth"
I
could say something about how you may have damaged your op-rod with rough handling already, but let's just assume that's not the case...
Have you ever messed with a Steyr M95, before? The Swiss advandced the straight pull technology quite a bit from even that level of refinement, which was, to put it mildly, still lacking at the turn of the century. Put aside the fact a pierced primer can throw the perfectly-intact bolt through your face, the spring-loaded camming of the bolt head was
very difficult to overcome when opening, and hard to control when closing, practically forcing the gun to be rammed open and closed (the "ruck-zuck" it was called). Seems cool and super fast until you take it apart and see how delicate the parts involved in carrying that effort are, and how prone to wear the design is. The early Swiss straight pulls were the same gun design under license (IIRC), to be later replaced with the true native designs in 1889, 1911, and 1931. The K11's are reportedly the smoothest (I agree in my very limited experience) owing to how the weaker/longer mid-body bolt lockup and camming geometry worked out, but those guns are markedly more cumbersome to deal with.
I'd also take issue with comparing the 'smoothness' of any straight pull to a turn bolt; show me a Mauser so "smooth" you can operate it in a straight line? No camming of the bolt head means by definition the action will be smoother, but only because it is doing less. Similarly, when comparing cock on open vs. cock on close actions (yeah, they're really smooth because there is no camming, but you are also fighting a spring on the way down which throws some people off). A Krag is supposed to be the best thing ever, anyways, but only because the action is, again, doing a heck of a lot less with its single lug design.
The Ross is also hardly a good comparison to use against the K31. Forget the bolt reassembly time-bomb-in-the-field (development could have fixed that) the interrupted thread bolt lug design is simply not particularly happy when unclean. Granted, the K31 wouldn't like that either (again, camming by definition doesn't care for grit, and it'd be an issue even in turn bolts), but a two-lug layout with a more enclosed extractor design likely stands a better chance. The threaded lugs do make for nice, slippery actions when perfectly made and clean (see the very pricey Weatherby vs. Remington 700, and Browning BAR vs. M1 Garand) since the more spread out metal/metal contact area drops contact pressure and thus peak friction when lubricated.
"P.S. It is pretty obvious what a K-31 op rod is and how it functions, what makes you think it is rocket science?"
He was talking about fracture mechanics and failure mode analysis, so yeah, pretty much a branch of 'rocket science' that is applicable to lots of things (technically fracture mechanics science got its start in the jet business, but whatever). The Op Rod is probably the weakest part of the K31 design, and was very likely accepted that way because 1) it is not load bearing and thus didn't need to be 'overbuilt' to hold back highly variable chamber/recoil forces, and 2) they didn't have a full understanding of how sharp corners and other features contributed to stress concentrations back then, and had to make a guess at how much something like this part had to be bulked up to make it through a rifle's service life (which they very likely did, in any case)
With as much money as the Swiss had, and as much affinity for fine firearms as they had, it should be somewhat instructive (if not definitive) that the K31's and 1911's have remained not only popular,
but in use for as long as they have.
"they don't HAVE a ranking, because they never went to war."
Way to 'win' an argument unfairly; there's lots of reasons the guns never went to war, none of them mechanical. In fact, it may actually be worth noting that the tactics the Swiss had the rifles slated for (defense, rather than offense, on home turf, with well provisioned/disciplined reservists), meant they didn't
need to perform as well in hellishly difficult conditions, but that the rifles had to be exceptionally accurate and reliable while clean to maintain that advantage (sniping from a distance). Different tactics, specs, and therefore, different strengths & weaknesses. Yes, "we'll never know" because the Swiss wisely stayed out and got rich instead of destroyed, so get over it and find some other way to compare the platforms than WWII military service in combat.
TCB