c0ommercial date?

[roc]

Here are some photos . this gun looks like it had been shot quite a few times. The bluing and straw are about 40%. I only shot once since I bought it about 30 yrs ago it worked fine. I must have lost the spring for the lock bolt when I cleaned it. can I find a spring for it or should i take it to a gunsmith also can anyone put a date on it or history. any help would be appreciated. those markings in the pictures are the only ones I could find. thank you again for any help.