The title of this piece is a question I often wonder about. Current
& recent manufacturers of ammunition often state their ammo will
last 10 years. From what I can gather about that, the consensus is that
figure is essentially made up for legal reasons but I am none too sure
that is the case. Many of the self appointed experts on ammo shelf life,
who tell you that seemingly have no clue if that is correct or if at
least some modern ammunition (that made within the past 50 years for the
purposes of this piece) will actually only last 10 years others say almost indefinitely. My guess is almost all quality ammo
will last much longer than 10 years but I wish someone could tell me factually how
long it will actually last. Those who write about it often make
reference to ammunition that was made 50 to 100 years ago that still
fires reliably and imply that today's ammo would be much the same. For
one example of such, see: https://www.nrafamily.org/articles/2019/10/28/can-ammunition-go-bad/
The thing is that ammo made more than 30 years ago has a good chance of having been made using corrosive primers (keeping it to western countries, East Bloc countries were still producing corrosive military ammo, I think, into the 1980s and may still be doing so for all I know). I have been told (personal communication with several gunsmiths, military collectors and ammo dealers) that it is a known fact the materials used to make those old time primers does not break down much over time and thus ammo from way back then often works just fine today if it was stored properly over the years. I have also been told that modern, non-corrosive, primer materials are quite different and will breakdown over a period of 20 to 25 years. Me, I don't know and I do not know if the folks who told me so actually knew and thus the question in the title: What is the shelf life of modern non-corrosive ammunition.
What I do know is there are poor ways to store ammo and better ways. I try using the somewhat better methods but do not go to extremes. So, I have stored it in climate controlled rooms inside sealed ammo cans for the most part. Climate controlled? Yeah, inside my house at ambient room temperature on the cool side - as in my basement. I also keep it at low humidity or at least try. So, sometimes I put desiccant pack into the ammo can along with the ammunition. By saying I do not go to extremes, I mean I do not do things like vacuum sealing every box of ammo or ammo can a some folks do.
What about results? I can say without a doubt, the ammo I have stored that way, so far, has all reliably fired whenever I have decided to shoot up some of the older stuff; some of that being 25 years old or older. Right now, I think the oldest commercially available defensive pistol ammo I have on hand is probably from the mid-1980s to mid 1990s. That is Winchester 9mm NATO FMJ ammunition. Never a problem, it goes bang every time. I think I have only a box or two of it left and doubt I'll shoot it; probably will keep it for nostalgic reasons. It is from the time when I with the U.S. Custom Service Office of Investigations running narcotics smuggling & money laundering investigations but also had collateral duties as a firearms instructor (no I was not a desk jockey) and got oodles of free ammo for practice to keep up my skills. I also have some older 22 LR ammo that still goes bang too, some probably from the 1960s or 1970s. Always amazes me that it still goes off if I shoot it up; the thing about it though is I'll not ever depend on it as defensive carry ammo but I might need to with some of my older 9mm someday. I know, I probably should have rotated it out years ago.
I also have some other old defensive pistol ammo in the form of Speer Gold Dot Hollow Point +P. I think I have around a case of that from shortly after 9/11 - replacement ammo paid for by my homeowners insurance due to loss of personal ammo I had stored at our range in 6 WTC on 9/11. That stuff, I think, needs to start getting shot up but right about now for practice. I am going to hate to use it because it is about 1/3 of my 9mm JHP and may be irreplaceable with current politics as they are but I doubt it will last forever so may as well use it up soon. Again, I know, I probably should have rotated it out years ago; yet, I am wondering if it will last another 19.5 years or so and still go bang.
Anyway - back to the question more or less: Does anyone here have any actual technical, manufacturing, scientific knowledge as to the shelf life of how long modern made non-corrosive ammunition will last and still go bang reliably? That it lasts well beyond 10 years, even 20 to 25 years if properly stored, is doubtless at least in my experience. What do you guys think?