New here, Seeking information

[SEMPERFIDELUS8403]

Hey Yall! I am new to this site and seeking information on a Model 510 "TargetMaster". I know from a site that it was produced in December of 1947 (Marked "DSS). During my research I found that there were different "grades". Where is this mark located? All mine says is "Model 510". It has some surface rust as it was stored badly (prior to the knowledge of its age). The stock is also beat up a bit. How can I best restore this gun to original shape? It fires perfectly, as I fired it this afternoon. Thank you for any info!