Studies also show that the vast majority of guns involved in violent crimes originate from federally licensed dealers that sell without a store front or proper record keeping. Shut these bastards down, require a valid storefront and proper record keeping for licensed dealers, plus a backround check and waiting period for purchasers (already in place in many states) and you've addressed a significant chunk of the ease of availability problem.
This shouldn't impinge most lawful gun enthusiasts too terribly much.
I don't believe this would help as there is a huge number of sales between private parties.
To have an effect, private gun sales would need to be outlawed...and that would be difficult to achieve.
...and most of those privately sold guns that wind up in the evidence room originate from these few rogue federally licensed dealers. People don't manufacture guns in their basement. Established companies do, and those companies sell to licensed dealers. It's a classic 80/20 problem. Cut out those few dirtbag dealers selling to everybody and anybody and you've removed a major source of the problem.
Primarily, it's an enforcement problem. Politically, pro gun politicians don't want to insult their pro-gun base and the well funded and organized NRA. This is the dirty little secret of the gun debate, and one for which neither the NRA nor their supporters have an cogent explanation.
Apparently, you are unaware of the huge activity in private sales of guns that originated from "storefront" gun shops.