I just had the urge to shoot my Webley mark IV yesterday so I bought it to the range with an ancient box of Remingtion .38 S&W 146 grain rounds. Half way through the box I notice that the shots started sounding different. I checked the bore for obstructions after each shot just to see if one stuck in the barrel (don't want to shoot a potential stuck bullet), but nothing. I just wanted to finish off this box.
By the end, I swear I could see the bullets traveling down range. I actually found four of the rounds. The four I found did not even make it to the back-stop at a 100 yards.
If the ammo was stored in questionable conditions, squib loads are not uncommon. Well stored ammo will last 100 years or more. For an example, look at the WW I vintage Militry surplus ammo available. Much of it is still very servicable.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball