I document my firearm sales by moving the gun to the sold tab in my inventory spreadsheet and adding a notation indicating the sale price.So it's my practice to document business/financial transactions.
A true statement. Your comment about doing the research is also apt, but both of the statements are wanting in terms of practicality for the average (or even the above average) person who is not a lawyer. It's a rare person who intentionally documents illegal transactions. The problem (as in this case) is that people document transactions they believe to be legal but end up being mistaken. This topic is relatively simple, but it should be pretty obvious from the comments on this thread that even gun enthusiasts often do not adequately understand the law or its ramifications.Of course things can get dicey when you document an illegal transaction.
The only way to really insure that you're not documenting an illegal transaction is to engage the services of a lawyer, or to do a really significant amount of research to try to get a good grasp on the particular legal topic (and all significantly related legal issues) in question. Maybe that's practical for some folks, but it's clearly beyond the pale for the average gun owner.
Let's say I add a date column to my spreadsheet. Now I've created the potential for someone to mine that data to try to provide evidence against me that I'm selling enough in a short enough period to accuse me of being an unlicensed dealer. The authorities would have had to do devote effort and funds to surveillance to gain that kind of information otherwise. It's highly unlikely that something like that would have ever come to their attention if I didn't provide it.
Let's say I add a buyer column to my "sold" tab on the spreadsheet and one or more of the buyers end up being a prohibited person. I can tell the authorities that I don't have to verify that buyers aren't prohibited, so I haven't broken the law, but how does that make me better off than if I just told them that I don't have to keep a BoS in the first place so I don't know who I sold it to?
Finally, most of what people consider to be "documentation" is easily faked. Short of doing all BoS' through a notary or using an FFL for all private transfers, none of the documentation provided would carry significantly more weight than the information in my spreadsheet tab, or, for that matter, my spoken claim that I sold the gun.
IMO, if the answer is that you don't have to do X, and doing X could potentially provide evidence against you, then, IMO, the average, non-lawyer is better off NOT doing X than assuming that doing it isn't going to be problematic.