That makes no sence to me what so ever. It is simply a matter of droping the go and no-go gagues. The go must sit below flush and the no go must sit above flush with the breech.

I'm not saying your wrong Charlie but why in the world would they need it to check headspace. The frame isn't needed at all. Did they give you a reason for this?

I could see them having to fit the barrel to some of the parts in the frame to get a good lock up.