You're getting there!

That looks like the front of every Krag magazine cover and receiver with typical stampings that have no specific relevance to identifying the rifle or valuing it. They are just considered stamps from different stages of production. Just a jumble of letters and numbers that we don't understand. The "P" that you see on the rear of the barrel and the front ring of the receiver signifies proof testing of each.

Need more pictures. You're teasing us!

Here are similar pictures of three different Krag receivers I took real quick for comparison:

Okay, I messed this up a bit but it still shows the rear sight well enough.

I can see a few details that can shed a small amount of light on your Krag. I can't see much yet but a couple observations:

The stock is cut down from a rifle stock to carbine length. It has been sanded heavily as seen with the worn down grasping grooves. The stock has a later M1898 bolt handle cut out which says the receiver is probably a Model 1898 receiver. The rear sight looks like an un modified Model 1898 rifle sight with the three notches.

The receiver does appear to have been scrubbed of any identifying marks. The left side of the receiver should show Model 1898, US Springfield Armory and serial number. This could be considered problematic as any firearm manufactured on or after January 1, 1899 requires licensing and registration by the BATFE.

Other important features are the receiver action, bolt and front sight. The barrel length is important also.

I can't see if the front sight is original or not.

Are there a couple of small holes drilled in the top of the receiver?

That looks like a great old sling with your Krag. Are there any cleaning rods or an oiler in the butt stock compartment?

Thanks for the pictures. Seems like you got it figured out.

It's great to have a family heirloom like this passed down from generation to generation. Congrats on having something like this in your family, even if it has been altered from original condition!

I have a '98 rifle.  Both front and rear sights are taller on the rifle but are very similar otherwise.

The barrels are both tapered and the muzzles are identical in diameter as far as I can tell without trying to find my micrometer.  Both muzzles are crowned identically.

I don't see any evidence of sanding.  Either you are seeing the effect of the light I was shining while the picture was being taken or I just can't see it.

The barrel is very close to 22".

There are four holes forward of the ejection port and two hole aft of the ejection port.  Decades of dry oil make it difficult to tell whether they are threaded.  45 years ago my cousin needed cash and sold the gun to Dad.  I have never seen a scope or mount on the gun but I have no idea if my cousin put a scope on it or whether previous owner did.  The holes are consistent with a scope mount.

I see what you mean about the grasping grooves.

The barrel is 22".  You had to make me go find that  didn't you .  I think the last time I used that was to measure a shotgun barrel.  I prefer the flexible cleaning kit.  Thanks guys I have learned a bunch.  I think I answered all your questions but if you have more or if I missed something let me know.

I went back over the gun with a light and I enlarged the photo of that area and I see no vestige of any markings but you guys have already seen way more than I have.