They aren’t “loopholes” at all. Gun sales have to conform to the laws of the state or jurisdiction, and it’s legal for me to sell my property to another individual in accordance with my state’s laws.
And I’m guessing you’ve never been to a gun show. I have, and I’d bet that 99% of the sales taking place are from FFL-licensed dealers and include necessary background checks. That is who rents tables and sells guns at gun shows. I’ve bought several guns at gun shows, and each and every one included a background check. The exception would be any deals that take place in the parking lot where Joe agrees to sell a gun to Sam. Whether a background check is required or not depends on state laws.
I also think you overestimate how many crooks go to gun shows or answer ads in their local PennySaver and buy from an individual in hopes of bypassing required background checks. I’m sure it happens, but many sellers insist on copying the buyer’s drivers license, which tends to drive away dishonest buyers.
I agree with statements above that FFL-licensed gun dealers are enormously careful with their required forms and record-keeping, as the BATFE keeps a very close eye on what’s going on. Straw purchases are by far a much larger problem than gun dealers selling to people who are not allowed to purchase.
As for buying in neighboring states, it’s not legal to buy a handgun from outside your state of residence. A rifle or shotgun, yes, but not a handgun.
I’ve been to gun shows too. Many will rent a table to anybody who wants one, and if you’re not a FFL dealer, you don’t have to (and in fact can’t) do an instant background check. Some of the big gun-show organizers have cracked down in recent years, but others not-so-much.
For that matter, I went to a show several years ago where an exhibitor had a table of guns “over here” that required a background check and another table “over there” that didn’t. (The two tables were adjacent. Apparently, he was a licensed dealer, and “over here” was from his stock, while “over there” was a private consignment. I’m pretty sure that was at least of dubious legality, but the show management tolerated it.)
Not in my part of the world they don’t. In deep-red territory (I’m in Kansas), there tends to be a great deal of suspicion that even copying a DL is creating a paper trail the feds could seize, so anybody who asks for one has seriously restricted his pool of buyers. A member of my in-laws’ family, e.g., built up quite a collection mostly through private purchases, and he advises he was never asked to show a DL, nor would he have done so if requested. (He has no difficulty passing a background check when buying from a shop, but politically he’s somewhere to the right of the John Birchers, and anybody keeping track of his buying is Obviously Up To No Good.)
This may be a regional difference, as I see from your profile that you’re back east.