Hey Nickel, I think I found you some answers....
this one "....Fresh casings have a shelf life of about two months if kept in salt and kept refrigerated. The sheep casings are very delicate and require more skill. Nowadays the fresh casings come on tapes or tubes so that they are easier to thread onto the filling nozzle and avoid the arduous task of unravelling a large knotted mass..... comes from what looks like a great sausagemaking website in the UK:http://www.sausagemaking.co.uk/
"WHAT IS THE SHELF LIFE OF NATURAL CASINGS?
Salt: 1 year or morePreflushed in Net Pack: 6 months to one year.Preflushed in Vacuum Pack: 6 months to one year.Preflushed on plastic Tubes: 6 months to one year.-Top-
WHAT IS THE BEST WAY TO STORE NATURAL CASINGS?
Store in the cooler at 40º (4.44ºC) or less in brine or well salted. NEVER freeze casings."
Comes from this website:
And you can check out the website below and ask them questions online:http://www.dewied.com/casings_hog.html
Looks like a very good company.
Hope this helps you out and good smokes to you!