and from the comments there:
Why would GLOCK need to see the Form 4473s? It is the qualifying ID that is relevant. A record of the buyer’s name and qualifying membership type should be sufficient.
Unless you can match a 4473 with a copy of the qualifying ID it means nothing.
It's like saying because my checkbook register says I have $500,000 dollars I must have it. What my register says doesn't mean anything unless I'm able to verify it with the official record at the bank. The copy of the ID is the check register and the 4473 is the official bank record. If they both match we're good to go, if not we have a problem.