This template gives you everything you need for a professional, customizable and legally binding Bill Of Sale Firearm.
Good idea to have one for your records. Federal law makes dealers do background checks, but private sales use Bills of Sale to document what happened.
Make, model, caliber, serial number, purchase price, when you bought it, both people's names and addresses. Check what your state wants too.
No, it just shows the transaction happened. No matter what paperwork you have, you absolutely still need to follow all federal and state laws for gun transfers.