I have a 30-40 Krag that I got from my dad.  I'd like to identify where and possibly when it was made.  There are no markings visible except by removing the stock and no serial number that I can identify. 
P.S. It is a carbine.
The only markings are on the forward end of the receiver.  Starting on the left side of the front of the receiver I have a 6.  In the centre cut out area there is a 0 and an 8 that are separated. On the right hand there is an N above a star, a J, another 0 and an 8 also separated and other marks that are too faint or double stamped so they are hard to read.  Any ideas would be appreciated.