Greetings again, and hope everyone is having a good Labor Day Weekend! 

I recently purchased a NOS Krag bolt that I believe is an 1898 (it at least fits and works flawlessly in my 1898 rifle; headspace is excellent).  However, I noticed that the bolt face and inletting along the bolt body are both blued.  I've never seen anything like that before (remember, I'm still a newbie), and yet I'm pretty certain this bolt is legit and has never been messed with or used.  Just curious if they came from the arsenal this way and why.   

Also would appreciate it if you experts can confirm that this is an 1898 bolt.  Even though everything fits/functions fine, I'd rather be 100% certain before I shoot my first round!  MANY thanks...

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