"cooking it more thoroughly" will only affect texture

they are ment to be heated, the ingredients will get over done and possibly taste even crappier
There are only 2 dangers in rations.. clostridium botulinum, a bacteria that makes a toxic, called botuline that causes botulism (deadly) and staphylococcus aureus (very common bacteria) that causes a toxic, that causes foodpoisoning..
The other common bacteria will die when they reach a certain temperature, eliminating the threat. Stuff like salmonella aren't dangerous in rations (they died, or completely destroid the ration..)
Those 2 that I mentioned make toxics, that don't dissapear by heating. The bacteria die, but the toxics are still there.
So if you open it, and it looks/smells edible, it probably is.. if it's discoloured, stinks of simply tries to crawl out of the can.. you'd probably better forget about eating it..
If a ration is stored with bacteria in them, they will already start growing quite soon, and the ration will not survive untill the expirydate.. The can get's inflated. Canned foods are actually most dangerous when they are fresh from the company (when it still looks and smells nice) or after 10+ years, when botulism has formed (it's a slow bacteria)
Moral of this explaination: If botulism is in there your screwed anyways
(I actually gave a german EPa entree (early 90s) to a friend of me a couple weeks back, that works in a labratory to check it on bacteria, and if it still meets quality demands.. test result was that it was still edible, no traces of botulism, but I'm getting the results soon and I'll post 'm here on the forum)
Sure, someone may one day kill me with my own gun.
But they'll have to beat me to death with it because it's empty.
A computer once beat me at chess, but it was no match for me at kick boxing.