Marlin 1893 .32-40

[Sneaky]

My girlfriend recently acquired an original marlin .32-40 lever gun. It's either the 1881 or the 1893 as far as I can tell. I have heard that the steel on these older rifles, being so old, can degrade with time and become unsafe to shoot. Is there any way I can tell whether or not it's safe? Should I bring it to a gunsmith? I have inspected the bore and receiver for cracks and it seems very sound. Any advice would be appreciated.