FWIW, stripping the bolt is not necessary if the gauge has a cutout for the ejector. Just remove the operating spring and slide and slip the gauge under the extractor lining up the hole with the ejector. Then headspace as normal, with light finger pressure only.

Headspace problems are uncommon with the carbine, since the cartridge setback is fairly light and most guns were not fired a lot (the M2 being an exception). Other problems, like muzzle wear and throat erosion are also rare, since cleaning was not as vigorous (non-corrosive primers) and the smaller powder charge and the type of powder used meant less erosion.

Jim