If you are doing any sort of build you really should check and verify the headspace before you go to the range. It’s becoming ever more difficult to get these gauges as they are precision tools so we took matters into our own hand. We contacted a precision tool and gauge maker in around our new shop (if you are thinking of a company name you are probably right :)) and send over some drawings from the SAAMI website and voila! They wanted more info so we got some drawings from Pacific Tool And Gauge. That’s right, these are made to perfectly fit SAAMI spec cartridges and Pacific Tool sanctioned wildcats.
Headspace gauges ground from hardened A2 tool steel. You ain’t going to wear these things out anytime soon.
We realize most folks are reluctant to buy an expensive tool to use it only once or twice so this is a rental program. Simply buy the gauges, use them (please try to be done in a week or so) and return them and we will refund you the price less a $20 rental fee for each pair of gauges.
You simply put this gauge in your chamber and close the bolt (action). Everything should lock up around the GO gauge AND the bolt should fail to lock up around the NO GO gauge. If she doesn’t close up on the GO gauge your bolt/chamber combo is too short. If she does close up around the NO GO gauge your bolt/chamber combo is too long.
The first this you do in one of these bad situations is do not fire the gun! Flag the build with a snag tag so that no one else uses it.
Either start swapping our bolts till you find a combination where the accumulation of manufacturing tolerances are in spec or take your build to a gunsmith to have the headspace fixed.