I have also noticed that drilling and I find it a very nice collectable piece of guncraftmanship. Sure that for his age (I also estimate the gun around 1880) he is is very good shape.
The rifle barrel is in 10 X 46 R and I have never hear of it.
Sure that Axel can clear this.
I think it must be interesting to see the proofmarks (if there are any proofmarks on the gun)
Marc.