My Springfield 30-40 Krag has a peep.
Mine also, had it when I was a kid, it's been gone for about 60 years now.
Like this one? The 1901 sight.
Is this the Buffington sight?
I have my FIL's old deer rifle in the safe. The receiver is marked "Remington model 1903" in 30-06 of course.
It has this exact sight. I have shot it well at 200 yds. Plenty good enough to split a military helmet at that range and a good deal further.
But it still pales when compared to the Lee Enfield JC with the precise ladder sight mounted on the rear receiver bridge.