Brass gets hardened by "working". Repeated sizing and firing will eventually harden the mouth area to the point it splits. .38 Spl will do this gernerally after about 6-10 loadings. If the brass was once fired sometime after WWII, it is still once fired and fine. Anealing to remove the work hardening is a PITA for somthing like .38 Spl. Shoot it till it splits and recycle it.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball
Brass does harden with age. But I don't know if 50 years is enough. I shoot many old guns, some that factory ammo has been discontinued for 80 years or so. I could easily see that ammo being brittle. But 38 spl brass is easy to come by so I would not bother to anneal it either.