Looks like they didn't use a safe edge file when they "adjusted" the barrel/cylinder gap. Should be able to make the marks "disappear" with some carefull filing and polishing. The cylinder face I'd run a stone across to remove any high spots and call it good.

X17s can have their actions lightened, but not as much as the centerfrires. DO NOT bob or lighten the hammer on a X17. You can run a Wolff reduced power mainspring if you replace the strain screw with a socket set screw to adjust the tension. A rebound spring (Wolff) between 11 and 13 lbs depending. With little work (pretty much just smoothing the rebound slide) you can have a 9ish lb DA pull that will fire bulk ammo nicely.