HA! - old but how old? Storage in a warm slimate or place in a house will really screw with the powder - and brass, as seems happened to these.

We've all fired off WW1 and WW11 ammo without a hitch, so it was probably the storage that hurt injured the rounds.

I recall ammo like that in the 50's and 60's - normal stuff. It might not b e very old at all, only 50 to 70 years.