Hellbound
Merchant of Doom
I could be wrong here, but I do have some knowledge on shelf-life items and it seems to me that the "useful" life of an explosive is less than the shelf life--in other words, once you pull that item from the shelf and install it, your time to use it decreases. I am not sure if that applies to C-4 type explosives, but I do know that it applies to other types of high explosives.
Well, yeah, to a degree. Think of shelf-life as something similar to MTBF on electronics or mechanical items. That's the average time at which the product will still be nominally useable.
Of course, after 10 years, it'll be at the low end of the spectrum, and that's the average shelf life. Some will be bad at 5 years, some might last 15, but it's a toss up.
Heck, MREs are a case in point. Supposed to have a 7 year shelf life, I got a rotted one that was 3 years old.