Is this another version of Fast' n Furious?
ATF Form 4473 instructions:
Question 12.d. Immigration Status: An alien admitted to the United States under a nonimmigrant visa includes, among others, persons visiting the United States temporarily for business or pleasure, persons studying in the United States who maintain a residence abroad, and certain temporary foreign workers. These aliens must answer "yes" to this question and provide the additional documentation required under question 18.c. Permanent resident aliens and aliens legally admitted to the United States pursuant to either the Visa Waiver Program or to regulations otherwise exempting them from visa requirements may answer "no" to this question and are not required to submit the additional documentation under question 18.c.Question 13. U.S.-issued Alien Number or Admission Number: U.S.-issued alien and admission numbers may be found on the following U.S. Department of Homeland Security documents: Legal Resident Card or Employment Authorization Card (AR# or USCIS#); Arrival/Departure Record, Form I94, or Form 797A (I94#). Additional information can be obtained from www.cbp.gov. If you are a U.S. citizen or U.S. national then this question should be left blank.
I own several weapons and I never filled out a form 4473. I only buy from private sellers. Not a loophole, just legal where I live.