Headspace is not a "perfect" thing. It varies with every different round you put in the gun. If your gun will not close on a no-go gauge that is .005" over SAAMI Max, it tells you that it will close on probably anything shorter, but how short? If it will close on a case that has been sized to .004" longer than SAAMI Max. then you know that with a round that measures exactly SAAMI Max. then you have a .004" headspace with THAT ROUND. The most consistent way to measure this is with a case gauge and I have found LE Wilson to be the best. They're cheap, stainless steel and you can see where every different batch of ammo falls. They will be different. The headspace is the distance between the bolt face and the case head as the round is fired. On Mike Bellm's T/C website, he sells an adapter for your dial indicator which when used with a case gauge of the Wilson type, will instantly tell you the relative length differences (shoulder to case head), between reloaded rounds or factory rounds, once fired resized loads, or reconditioned rounds. Suppose you bought ammo that has been reconditioned, brass once fired, and it was first fired in a gun with excessive headspace, then compressed way to back where it started out, you might encounter a problem like you have, with brass that has already been compromised by overstretching and overresizing. Headspace is the stepchild that is kept in the corner in the gunsmith world by many; it's always changing and frustrating at times. BTW, how do you know that a no-go gauge is .005", over SAAMI Max.? The gauge will tell you! Simple. If your gun does close on the no-go gauge, you have an issue with the gun itself; it shouldn't if it is within specs. Your gunsmith apparently isn't "seeing" anything wrong, but I hope this is based on good measurements, for your sake. Additionally with stainless steel cleaning media available today, fired, cleaned cases look better than factory; you'll never tell the difference by looking at it.