BP wrote on Jul 4
th, 2015 at 3:04pm:
What affect does that 1/8th of a turn out have on headspace?
Strictly speaking, backing out the screw to "tighten" the action will increase the headspace, but by such a small amount that's it's negligible.
(The drawing at the link shows the central-extractor action, which does not have the screw.)
Properly set up, the face of the breechblock should be an .001" to .003" interference fit to the face of the barrel when the action is closed, and that will provide tension to the lever. At the same time, the back of the breechblock should be in contact with the small shoulders in the frame, which takes much of the thrust on firing. You can test this using a strip cut from a thin plastic bag, (0.4 mil) as a feeler. Early (side-extractor) 44s that have come to my attention all seem to be pretty well fitted this way, BTW.
If there is clearance at the breech face, cock the hammer and try levering the breechblock up a little at the back. If that closes up the gap, you have proof positive that the link needs rework. Worn or bent pins, and battered pin holes, will allow the breechblock to stop short of its' full-lock position. This is so common as to be endemic in almost all well-used 44s we find in attics and at gun shows.
The proper fix is to ream the various holes to fit slightly larger pins. It that doesn't do enough, the barrel must be set back.