[Archarris]

So I have a fairly early Springfield 1903. Made in '23 I think. It was sporterized years ago by my grandfather. Now this rifle is just a shooter and is used for deer. On the inside left side of the receiver, maybe 1/2" behind the ejector is a small silver bump. This bump contacts with and has caused considerable wear on the portion of the bolt which straddles the ejector when the bolt is worked. It causes the bolt to be somewhat difficult to open and close. My question is what is it? Thanks for the help in advance.
Stephen