Originally Posted by z1r
A sticky bolt lift can be caused by many things. One of the best ways to verify setback is to pull the barrel and inspect the lug seats.

Mausers are tricky to diagnose due to their split upper lug. When the lug seats set back, a ridge is left due to the ejector slot cut through the upper bolt lug. This can lead to a false "good" reading if you try to use a headspace gauge. Because, as you rotate the bolt into battery, the bolt lug contacts the ridge and is forced forward into the gauge. The gauge being hardened steel, doesn't compress and will read like the headspace is fine. However, if the bolt would be allowed to go into full battery, then the excess headspace would be apparent.

In all the Mausers I worked on that had setback, not one had the bolt lugs set back or cracked. The setback was confined to the receiver's lug seats. The only Mauser bolt I saw with a cracked lug was an FN commercial. This due to the fact that the entire bolt was heat treated again after the swept bolt handle was welded on. Early commercial bolts were repurposed military bolts that had the new handle stick welded on. Then the bolt was re-heat treated. This of course resulted in a bolt that was too hard.

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Did not intend to imply the bolt lugs actually get set back much, but rather they crack. I can find several bolts here that look like your picture just before the lug calves off. I can also dig out bolts that show tiny incipient cracking either through the lug or in the bolt body.

I do appreciate the commercial mauser information as several have been FNs.

Mark Begich, Joaquin Jackson, and Heller resistance... Three huge reasons to worry about the NRA.