Thank you all for the advice on the books....
1st one I got was Mr. Poyer's  [2nd edition revised] and just received Col Brophy's [1st edition BeinFeld] and Mr. Mallory's (2nd Edition SRS) in the mail - so sitting down to read them as I can...
I'm awaiting a reply from the seller of the rifle - & it would be a great addition to my Krag carbine...my concern was the barrel condition of the rifle....the measurements I posted are from the Carbine (which I haven't taken out to exercise yet) - just barely found some 'food' for it.