OK so I got a field guage. Dropped it in both my ARs and with finger preasure the bolt did not close and the carrier protruded from the rear of the upper.

Now should I have used the bolt carrier? I did not slam it home? Just rested it on the guage and finger preasure? I thought I saw a post where they said dont use the carrier.

Anyway the guage fell on its own from one of the ARs and fell with a tap on the guard from the other.

Am I good?

To use it properly, you have to strip the bolt, take the extractor and ejector out. Then see if the bolt will close and turn with light finger pressure. If you can't reach down to the chamber with the upper assembled, a section of PVC pipe just big enough to press over the bolt tail, six to eight inches long, will do the trick.

Slamming the bolt home on a headspace gauge is like tightening a micrometer with a torque wrench.

It depends on if you have a military field gage or civi field gage. The military one is relieved to allow you to use the bolt and carrier as is. The civi one is not.

Quoted: It depends on if you have a military field gage or civi field gage. The military one is relieved to allow you to use the bolt and carrier as is. The civi one is not.

Yes this was a military gage.