What does Nitro (proof) really mean?

[Marplot]

I just acquired an old breech loader and has the picture on the barrel. It could be late 1800s or early 1900s. I think that it means it was proofed for smokeless, but it is easily over 100 years. It it probably safe to shoot target loads?

It also appears it has old case hardening. 12ga

 

[anonymouscowherd]

Yes it was proofed with/for smokeless

Since it is pre-standards unless there are other marks I would stick with light target loads anyway