The shelf life of gun powder largely depends upon how it was stored. If it was kept in a sealed can under cool, dark, and dry conditions, it could last for decades or longer. Heat, light, and humidity are the major factors that will cause degradation.
Some guys are still using up stocks of the WWII military surplus 4831 powder that Bruce Hodgdon bought right after the war. Some loaded ammo made prior to WWI is still viable. After my Dad died, I used some of the opened cans of rifle and pistol powder he had. The price tags on some of them were under $3.00 per lb. so it probably dated back to the early 1970's. It worked just fine. Degraded powder will often show a change in appearance, smell, or color, and should be discarded.
When I was still in high school, my buddy's uncle gave us a bunch of old WWII C-Ration packs. The canned food we tried wasn't very tasty, but I never heard any old soldiers raving about them either. The Hershey chocolate bars were mostly white in color due to fat-bloom. My buddy's Dad smoked some of the cigarettes that were included in each ration pack. These were all non-filter Camels, Lucy Strike, Chesterfields, Pall Malls, etc. He said they were pretty stale. That said, it might be a good idea to keep your old MRE's just in case the Democrats ever regain power and totally mess things up again.
