Travis,

A couple comments on your Krag. It's quite a treasure to have a functioning rifle that belonged to your grandfather. I have an old shotgun of my grandfather's that doesn't function but I love having it. Since I love Krags, I would cherish one belonging to my granddad!

Your Krag receiver has been drilled for a scope mount. I don't know which one would fit but that is why there is no rear sight.

The rear sight for the Krags all have the same screw holes. All Krag sights are inter-changeable but the hand guards, which yours also does not have, are different for different rear sights.

You might have a replacement barrel on your Krag. It also might have had the two rear sight holes filled in. I cannot tell from your picture.

The cut out on your barrel is a dove tail that has been made to slide in a rear sight that fits that specific dove tail. I had one of these on a Krag I got years ago.

So, you can use a scope or find a dove tailed rear sight that fits.

Others may chime in to add more info about the receiver mount for a scope or other details.

Hope this helps some.

Good luck and keep us informed!