I have been seaching for this info but can't find it. I am curious, what is the difference in length between a go, no go, and field gauge for a 7x57 or .257?

hmm, i don't know .. is the 257 remington roberts shoulder angle different than the 7x57? the 7, 8, 9, and 9,3x57 are all the same datum, but i don't know on the bob

The 7x57 and .257 Roberts use the same gauge. There is a difference of .004 between the go and no-go. I don't know what a field reject gauge would be, but typically they are in the neighborhood of .004 beyond the no-go.

Thanks Westpac, that is about what I was thinking. Not a big deal, I was just wondering. I appreciate the info.

Typical difference is .004" per step ie go would be right on the money. No go would be +.004" and a field reject +.008 (all dimensions give or take and your results may vary)

Having never served in the military I've read and heard rumor that a field reject gage was the "worst case scenario" and a rifle was still fieldable if the bolt would not close on the field gage.

Keep in mind that this was for service rifles and not a commercial arm or any sort.

Apparently there's no standard for "field" gauges, at least not for .223 Remington. Yesterday a local Sergeant from the SWAT brought two rifles that had bolts closing on his "field" gauge from Forester. Turns out my "field" gauge from Clymer is .004" longer than the Forester gauge, and those bolts did not close on my gauge. His "field" gauge was .006" longer than the "GO" and my "field" gauge is .010" longer.

Were the rifle chambered in .223 or 5.56 nato. As there is a difference Albeit not much but there is a difference none the less.

That could account for a difference but all gauges used were marked ".223 Rem"