Because I am just applying for my FFL after 12 years of working on firearms I never took serial numbers. This was my client's great grand father's new Model 99 in .300 Savage back in the 30's. It was in good shape except for dry wood and dirty action from old oil and some spot bluing had to be done.
p.s. I have fund many people want to buy and sell guns but not work on them, that's my niche, refurbishing older firearms, from flint locks, cap and ball to WW2 rifles and pistols down to newer shotguns, rifles and pistols that need a little TLC and some repairs.