My experience with Kitty-Kats is that they run fine out of the box, and have a properly sized gas port.

I have mine on an RLL-equipped stock DPMS lower, with a telestock and standard carbine buffer, and it runs through mag after mag after mag of brown bear on full auto with no issues at all. Brown bear is notably hotter than many commercial brass loadings, and definitely hotter than tula/old wolf.

If it FTXs with many different types of ammo, then it's likely a chamber issue. Clean the crap out of the chamber and polish it with a .410 shotgun mop coated in flitz, on a cleaning rod chucked into an electric drill.

If you wish to upgrade your extractor, get the black insert, and extra power wolff spring. You can also stick a #60 viton o-ring (viton for higher heat resistance, as regular o-rings will melt in an AR bolt at operating temps) around the extractor insert for even more stiffness.

Different buffer weights are generally used to fix timing, bounce and recoil issues, not FTX.