no go or field

[Milsurp Collector]

You will still be "information short". If it does not close on a field and does not close on a no-go , you still will not know if it will work till you check it on a "go" gauge. For what you are doing , you need all three. If you are buying a used gun you should have all three because you do not know how long the parts of the gun you are looking at have been together. If you know the gun has been shot "as it is now in your hands " , then you know it should close on a go ( that's how it got in the used condition). Being used , it may close on a no-go. If it does not , that's good , if it does , it tells you little. The field is the deciding one, the buy it or leave it test , and therefore the one to have if you can have only one. Chris

I understand what you are saying, and I agree that if you only have one the FIELD is the most useful. In my opinion a GO gauge is useful if the rifle has a new (as in brand new) barrel, but otherwise isn't essential for me, as I have no brand new barrels that might be short chambered.

Since I take the bolt apart to check headspace, and there is no firing pin, I use a M2 round as my GO gauge. Again, disassembled bolt with no firing pin, just receiver, barrel and bolt for the test, no stock, trigger group, op rod, etc.