Originally Posted by Big Papa Pink
Yeah, I was going to recommend giving them a call. I would think that if the piston is leaving scratches in the inside of the reg, that that would cause issues with it's functionality. I would suspect you would want to replace that piston before more damage is done.
They actually suggested just taking some fine grain sand paper to the piston to smooth out the tool marks, so I'm going to give that a go this evening.