Uncle Ike - Welcome to the KCA Forum.

Your U.S. model 1898 Krag, #213686, was originally assembled around June to July, 1899.

It is likely a Krag infantry rifle that someone has 'cut-down' the stock and 30 inch barrel for convenience in Hunting.

Only about 5,002 model 1898 carbines were made and they normally fall in the number range of 117536 to 140195, (mixed with lots of rifles).

Your stock 'acceptance cartouche', "J.S.A. - 1899", is for Assembly Room Assistant Foreman, Joseph Sumner Adams and the year it was inspected and accepted for service.

The 'Circled P' stamp indicates the Krag was 'proofed' and function tested. The small number nearby is a Stocker or sub-inspector stamp.

The "U" on the barrel-band is an assembly aid and should be on the Right-side of the rifle.

If your Krag is a 'cut-down' rifle, as I believe, it would be worth about $270 to $300, in the condition you describe.

Close and clear pictures of your Krag's rear-sight, front-sight area, and forearm tip, would allow confirmation of my 'hunches'. 

(p.s. - As a 'family heirloom' and fun shooter, such altered Krags are priceless)!