[4V50 Gary]

I chambered my barrels with the receiver off.

I put the stripped bolt into the receiver and measured at four different places (12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock) the distance of the bolt face to the receiver face. I then used the largest number. This is subtracted from the shank length (let's call it headspace distance).

When I put in the headspace gauge into the barrel, I measured the distance of the end of the shank to the backside of the headspace gauge. I then used the finishing reamer until the the distance of the headspace gauge protruding from the barrel equalled the headspace distance discussed in paragraph #2.

Afterward the barrel is installed into the receiver and the bolt inserted with a go gauge. If it closes easily, then it is tried again with the no go gauge. If it doesn't close, you're good to go!