Craig never came out and said he never saw a Mauser after he stated that he witnessed one. So no, he didn't "change his story" just because he didn't state it again years later.
Why did Weitzman change his story after he said he witnessed a Mauser?
Why would a Sheriff claim to just "glance" at the possible murder weapon? Wouldn't he fully inspect it as part of the investigation?
If you don't see the inherent contradiction between Craig's 1968 story ("I didn't know what it was") and his '70's videotaped interview ("stamped on the barrel was '7.65 Mauser'), it can only be because you are trying very, very,
very,
very,
very hard not to.
If you don't at least wonder why Craig failed to mention seeing the '7.65 Mauser' stamp on the rifle in his Shaw trial testimony, it's because you simply wish to be incurious.
If you don't think twice as to why Craig didn't mention the stamp in
When They Kill a President , you just don't want to think.