Here a nice piece of wood has been added to the top of the stock with ivory plugs over the screws.

Rifling still there, looks like a bit of rust on the lands.

These photos were taken with a bore scope camera. Not 1082 quality but enough to show some detail. I can use other cameras if necessary to show more detail.

Thanks everyone for taking the time to have a look at this. I did call the number I had for the gun works, but the guy who answered the phone was only in business since 1980 and has since retired, so he couldn't have done the work. I was hoping he was a 3rd or 4th generation craftsman who took over grandpas' business. But no such luck.

Rear sight does not have a micrometer type adjustment, the screw  was adjusted to touch the top of the sight base so the elevation would return to zero when the staff was taken off for bolt removal.  Not sure but IIRC the screw on my Redfield 102 was 4X40.  That would give you about 3 1/2 inches per turn at 100yds.

I patched the barrel before shooting today and the patch came out  green, so I'm going with what you said, it's copper and not rust.

Here is the result of my shooting today.

Shot the 1898 Krag today in the 100 degree Texas heat. First four rounds, all shot at 100 yds were Remington 180 gr that I pulled down and reduced the loads by 3 grains out of original 47.5 of extruded type.
NOTE; round 2 is out of picture at bottom of paper. I held low because I had thought round 1 went over top of target (big puff of dust). Only after first two shots did I pick up my Savage and look at target through the scope, surprised to see both rounds landed on paper.

I adjusted the sight and launched two more hitting at 3 and 4 o'clock and checked the breech again for any signs of problems. Expelled cartridges look good except for round two that had a primer sitting slightly proud.

I  then shot one un-altered round. LOTS of case stretch near head. Probably not re-loadable.

I switched to Winchester 180 gr. Super X ammo shooting 6, 7 & 8. Cases looked much better and rounds landed only slightly high. Feed from magazine although not problem free but not bad overall.

Rounds 9 & 10 were shot after a half hour cool down. Not sure if barrel temp, absence of mirage or my shooting were the reason for the lower impact point, but still….not bad for a 117 year old rifle with iron sights and a half- blind nut (or maybe a half blind-nut) behind the wheel.

I'll measure the brass with my headspace gage and see it I have a head space problem.

If I do have excessive head space, what if any are my options?

'Texas10' - Head-space is not measured on the fired brass.

Head-space on the Rimmed .30-40 Krag Cartridge is basically the distance from the barrel breech, (where the front of the cartridge rim stops), to the front of the bolt-face, (ignoring the bolt flange).

Generally Krags do not show head-space issues.

Many Krag shooters back off their full length Sizing Die a turn or two, to avoid unnecessary working of brass.

I just use a Field Gauge (.073") and don't worry further, if a Krag 'Passes' (bolt doesn't close on Field Gauge).

(p.s. - disassemble bolt and just use the Bolt-Body in Action, when checking head-space).

Went and checked the screw in my 102K, mikes .122 in diameter and is not a tight fit.  Said 4X40 because that is what it looked like to me.  Despite a slew of reference books I couldn't locate one that had screw diameters to verify size.  When I bought the sight there was a screw in a little bag marked as .125 dia. and 40 TPI, but it was bent buggered up and half the head broken off.  It will barely start and I did not force it for fear of damaging the threads in the slide.  Suggest you try some of the bigger hardware stores, they usually have a election of small screws that you can try in the slide.  Worst case get a fine thread screw slightly larger and drill the original hole and tap it for the new screw.