Ned,
You can use just a no-go guage. If the bolt closes part way, but not all of the way with the guage in, it should be ok. With the rifle pointed in a safe direction, if the bolt closes normally on a factory cartridge and does not show any signs of crushing the cartridge, minimum headspace should be fine. It is always best to use go and no-go guages if they are available. If the rifle has been rebarrelled use the go and no-go before loading a live round. I assume that you have a used surplus rifle, so more than likely minumim headspace should not be a problem. Be sure to strip the bolt prior to checking the headspace and also clean the chamber. This is the only way to get an accurite reading. If the bolt closes on the no-go guage, it would be best to either pass on the rifle, have the barrel set back and the chamber recut, or have the rifle rebarrelled. Use your best judgement and consult with a local gunsmith if you have any questions at all. If you already have the bolt stripped and the chamber clean, I doubt if a gunsmith would charge much to check the headspace.
Good Shooting-John K
