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Military Firearm Restoration Corner

Bolt Forging Oxide Color Question


drgoose

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OK, I recently just bent my first bolt. Actually it was not me, but a local gunsmith I found who did not mind me looking behind his shoulder while he did it, but anyway. Thanks to gun nutty I was reading in a chapter on metallurgy that polished steel will produce an oxide film after being heated and the color of the oxide film can be used to guestimate the temperature of the steel. Below is a magnified picture of the root of the bolt we bent and I am wondering if I am reading this right.

 

OxideColoringinBolt.jpg

 

Mauser4.jpg

 

Mauser5.jpg

 

OxideColors.jpg

 

And if I am reading this right, I still don't know what to do with the information. I want to conclude that the temperature of the bolt did not rise significantly on the areas where no oxide film was deposited. Is this correct?

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Yes where the color didn't change there was no change in the temper. I see the cocking cam is still bright, I good indacation that it was done right.

Don

 

Does the cocking cam participate in absorbing energy from firing a round or is it just the two locking lugs?

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As GN said the cocking cam just pulls the cocking piece back. On a cock on close action like the swede you won't notice the effects of a soft cam as much as a cock on open action. The extraction cam on your bolt was heated though. That also isn't as noticable in a c-o-c action since you aren't trying to fight the forces of cocking and extraction at the same time like a c-o-o action.

Don

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