I suspect that they can. FFLs have wide latitude in refusing to sell.
Otherwise the government provides the FFL the ability to throw their hands up and say “I had no choice but to deliver the firearm for money because the government ordered me to complete the sale”.
Their loss will be someone else’s gain. Sale will move to another store. Supply and demand. And if they completely cut off legal supply, the illegal will do just fine.
It has in the hood for decades. No problem solved, but a liberal feels good, that’s what it is all about.
There are thousands if not millions of teens throughout the nation who have guns for hunting and plinking. They are responsible owners who enjoy the outdoors. They live in the block red counties on the electoral maps, their parents voted for Trump. For country kids, this is an age old custom and a good one. Many volunteer for the armed forces and drill sergeants love them for they are already good with firearms. If the age for owning or purchasing firearms is raised to 21 it will make them illegal owners and seriously have a negative affect on millions of Trump supporters.
Besides, these matters should be the responsibility of the various states, not the feds, IMO.
I’m still wondering why there haven’t been any gay couples that have gone to bakeries in Dearborn, Islamberg, Patterson, Brooklyn, Minneapolis, Portland-Maine, Tampa, Hicksville, and asked any Muslim bakers to bake them a wedding cake.
As for the age to buy weapons, I’m waiting for a sensible(hard to find, I know) member of Congress to put a bill forward saying that if they’re raising the age to buy guns, then the ages to vote and join the military go with it.