Very easily
How to Buy a Gun in 16 Countries (Published 2018)
Many Americans can buy a gun in less than an hour. In some countries, the process can take weeks or months.
www.nytimes.com
lol even full-blown commie states like mine aren't this strictAustralia 1Join and regularly attend a hunting or shooting club, or document that you are a collector. 2Complete a course on firearm safety and operation, and pass a written test and practical assessment. 3Arrange firearm storage that meets safety regulations. 4Pass a review that considers criminal history, domestic violence, restraining orders and arrest history. Authorities may also interview your family and community members. 5Apply for a permit to acquire a specific type of weapon. 6Wait at least 28 days. 7Buy the specific type of gun for which you received a permit.
in most US states you literally just go to the counter, show you're of legal age (if that idk), and buy the gun