I've tried all the ammo that you've listed and my results varied some. Had good luck with the Fed Lightenings, Remington Golden Bullets, Remington Thunderbolts, Winchester Super X, and Winchester wildcats. But the Winchester X-perts weren't worth buying. Remington Thunderbolts are my choice for cheap ammo. I couldn't even get the Winchester X-perts to shoot well in my 10/22, just not very accurate.
You mentioned the Remington Target ammo and the CCI Stingers, both of which I've shot through my KMK-512. The CCI Stingers are great, thats my choice for hunting squirrel with my MKII in the fall. When my gun was new I had trouble getting CCI ammo to extract, but after breaking it in good it loves Stingers. I wouldnt waste the money on the Remington target ammo, it's JUNK! A friend and I both bought some and had bad luck with it out of every gun we tried. First we tried it in our MKII's, neither of which shot consistently and we found a LOT of duds. Had much the same result with my 10/22, marlin semi auto, and his Henry lever action.