Ok, I see a couple of things in that picture:
1) There is a carrier key shaped yield mark in the top of the ring. This may have happened several ways, but if the key can strike there when firing your buffer or tube is out of spec.
2) The buffer tube does not appear to be screwed all the way in. This could be part of problem #1 above, allowing the buffer to travel farther before contacting the bottom of the tube.
The marks in the face of the anodized buffer appear to be chatter marks, and may have been there for a long time.
To check the location of the buffer detent, assemble the tube/spring/buffer on the lower, and place a straightedge across the top third of the buffer. It should protrude slightly from the face of the receiver ring, allowing for a slight preload on the bolt carrier assembly when the weapon is assembled.
Colt (and many others) drill the detent hole at an angle, so that they miss the top of the ring with the drill body. Some manufacturers used a reduced shank drill, and went straight down. Still others cut a small portion of the ring away, and drilled straight down.
If you need to move the hole, you should use an aluminum plug to fill the old hole first. The best thing to do is bore the existing hole oversize to about .375, then press fit an aluminum plug in the hole. Done carefully, this repair is almost invisible & can be anodized.
Lem