gas rings burning up?

[zero G]

So I examined the carrier, the chrome inside seemed smooth. The key is tight and staked. Then I ran a sharp pick down the inside walls of the carrier. There are some noticeable grooves at the very tail end inside the carrier where the hole for the tail of the bolt is.
I don't know if this is normal or not.
I'll have to check out Arf.com like klem was saying. Also when i was looking around earlier, there was some talk about some these guns being overgassed like A5 said.