Trapdoor Rifles

I just bought this off ebay last week to replace the pitted chamber I discussed on another post. Anyways, I was intrigued that it was wearing a Krag 1902 sight. I got it today and see that someone drill and tapped (to the original x26 tpi) a 3rd hole so it would accept the Krag sight. Its been there long enough that its created witness marks on the BBL, so its not a 'recent' addition. As Im building this gun s a 'shooter' and its never going to see more than 100 yards, I may even keep the Krag sight on it. Has anybody ever seen this or is it a one of a kind bubba?

I saw that barrel on eBay. I've never seen a TD with a krag sight on it until then but I've only been collecting them for around 15 years now.
My guess is that bubba changed the sight many years ago.

Yep

Do I see the “Sargent’s Peep” flip-up on the back of the eyepiece?

Yep, thats the SGT's peep sight on the back. I was intrigued with it but eventually swapped it out. The third hole is now visible (the bubba hole). Normally Id fill the hole and reblue the area, but there NO way Id be able to match the patina on a 140 year old gun. I can deal with one errant screw hole as long as this new bbld action shoots well. (I installed a Buffington sight in its place)

Since it's just going to be a shooter anyway just fill the hole and re blue just the barrel , not the breech.
I have a rod bayonet rifle that someone spilled or even tried to strip the barrel, problem was that only the middle of the barrel had no blue on it. I took the barrel to a gun smith down the road from me and he blued the barrel but not a shiny blue. He didn't blue the breech as that area was fine and the blueing job he did on the barrel matches perfectly!! Until you look real close you'd never know.
Just an idea to rid the barrel of that 3rd eye

If nothing else, how about running in a screw, carefully filing/stoning off the head and bluing that spot with a Q-tip?

I know how to hot blue, I know how to cold blue. These old guns were 'rust blued' and the patina is now brown. I know of no reliable way to mimic the old school 'brown' without subjecting the entire part to a rusting booth. (I do quite a bit of rust bluing and have had varying success, but I dont think I could do it on a small spot on an otherwise all original barrel.) This is one of those instances where messing with it is just going to make it worse.

'Twas me, I'd put a blued filler screw in the hole and leave her be. I've spent too much time turning small flaws into bigger ones!