Im in the process of cleaning guns on this rainy day and im noticing the gas piston is wiggly but it wont unscrew also there is some rubbing marks on the bolt carrier. Is this a problem? Or just let it be?
Mine is the same way, wear on the bottom left of the carrier and the piston wiggles but is still in working order. Unless it is quite a bit of slop, like gaps showing when moved side to side, I wouldnt be too concerned.
Some wobbling is just fine, it is actually by design to allow for loose tolerances. The wobble is to allow the piston to stay (find the center) of the gas block as the action cycles.
Usually at the factory the piston is screwed tight then backed off 1/4 of a turn or so and pinned.
So don't worry about the wobble, but check the piston for cracks occasionally.