I have been using a Parts Unknown rear sight for my iron sight shooting. This one has a long staff and it's disconserting to be
able to move the staff very, very slightly backwards and forward. I do recall in shooting
the M1 at 1,000 yards one always "set" the sight just before each shot
by applying a bit of pressure downward and forward. I do this with
the above mentioned sight. Also, need advice as to compensating for the slack in the verniers; should I go past a mark and then backup to
remove the slack? Any suggestions or opinions as to the sight itself or
techniques using it would be greatly appreciated.

fred

Thanks for your comments, I'll do some measuring. The sight in question returns to battery o.k. but when in that position there is
a couple of .001's wiggle back and forth.

fred

Also, so far as lost motion in the adjustment threads goes, not to worry.

If you're moving the sight to align the vernier marks then it doesn't matter about pre-tensioning the threads, the alignment will be the same regardless of any pre-tension from either direction.

If, however,  you're moving the sight a certain definite distance or adjustment value past or before a certain mark on the scale, then the adjustment must always be made from the same side in every case, so that the thread pre-load (and thus the sight's actual movement) are the same in every instance.

This applies to all instruments that use threads as the sole agent for positioning the adjustment, such as most mechanical iron sights. Most scopes however, especially internal-adjustment ones, also use a spring to (supposedly) take all the slack out of the adjustment.

If you trust this spring and its lubrication & free movement, then you don't need to worry about pre-tensioning the threads. If you're not quite sure, then always approach the new sight postion from the direction that increases the spring tension. I don't worry too much about the external-adjustment scopes 'cause their springs and tubes are visible and can be manipulated to ensure the same relative position to the adjustment knobs, but I ALWAYS double-ensure the adjustment on the internal-adjustment ones, by approaching the new position from the tension-increasing side and then tapping lightly on the turret with the back of my Swiss Army knife.

(You don't carry a pocketknife? Then you have my utmost sympathy, 'cause you're obviously not from the South...............VBG!)
Good luck, Joe