Inland Bolt

[painter777]

First thought.............. Where is Newscotlander??

See that it's a pointed right lug.
Also see that the I.O. stamp is the later style with the O being taller and narrower than the early rounded O.
I don't know if Stan Pro made the later pointed lug flat bolts.
Have read that early Stan Pro bolts were stamped on the big right lug up to a certain number.
Riesch 6th edition says some were just a S. Followed by a S and number up to S43 on right lug. Then moved their stamp to the small left lug, stamping from S44 thru S53. BUT the few Stan Pro bolts I have here have a different style S aka Sans Serif.

May be as easy an explanation as a rarely seen inspectors stamp on a very early pointed bolt.
More than likely not correct because carbines can't be that easy. I did manage to burn off the afternoon looking for a correct answer for you but missed my favorite tv show while doing so.
Oh Well.............. Rifleman will be there tomorrow!

Just curious Rusty.......... Is the proof punch in the usual spot on top of the bolt?

Gave it a shot Buddy

Cheers,
Charlie-Painter777