Brush the effected areas with 4-ought wool, wipe off with a dry cloth and keep an eye on them every month or two. Don't spray them with WD 40 or other lube/moisture displacer as that can get past the primer in some instances.
; Old brass, especially those with murcurical primers (very old brass) becomes brittle and sometimes splits when fired.
; It is best not to fire corrosive (murcurical) primed ammo as the bore must be cleaned with water or water soluable oil to break down the salts left. This brass cannot be re-loaded as the murcurical priming's fouling inside the brass, as little as it is, still degrades the brass making it even more brittle and dangerous to use. I suppose you could wash the brass as if it were used with black powder as that will neutralize the fouling, same as water will in the bore when corrosive priming is used. Best not to fire it, period. With all the brass available today, coupled with form dies for making about anything, one should use modern made brassonly.