This is a nasty one. It
isn't a 'Missing Die' forgery, and it does appear to be a genuine type.
However, the print appears to be a bit too good, and the paper looks to be a bit too smooth. (Incidentally, Cjd, can you check the paper, please? It looks like a European wove, or possibly a good quality 'native' paper.) If it's on a European wove, it's a reprint. If it's on 'native' paper, it's almost certainly a reprint also.
The genuine originals look a lot messier, like this SG 5a

or this SG 8

This Web site
http://www.kashmirstamps.ca/index.html will tell you just about everything you could conceivably want to know about the stamps of Jammu & Kashmir.
Whatever, it's a very nice example of the 4 Anna. Hold onto it, to use as a comparison against the forgeries of the Jammu & Circulars that abound. There are some of them on
ebay at the moment, as usual.