I bought 200rnd of "Maxtech" 9mm once, brass jacketed bullets. 4 out of 200 would not fire in my Sig P320 M18. They simply failed to ignite when the primer was struck. After giving them time for hang fire, then left them sit for a few minutes. I unloaded each as it occurred and loaded them in my XD-M Elite OSP Tactical that has a stronger firing pin strike than the Sig. It fired 3 of the 4, so only one dude "sort of" out of the 200. But compared to other ammo that I have never had a single problem, that says poorer quality for that ammo, IMO.
I have a Ruger 22/45 Mark III that will suffer feed problems after it gets dirty with anything but round nosed high velocity rounds. But that is more of a .22LR thing, both the Ruger and the ammo and how dirty it is....
As far as ammo going bad, good ammo is sealed.... I have surplus ammo that is a decade old, including surplus Mauser Ammo that is decades old, never had a problem with it... ....it can go bad with time and exposure to the elements, but I simply haven't experienced it.... ....all my surplus ammo is military surplus (meaning it was high quality) or my cheap ammo I shoot right away...
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