The U.S. population is over 328 MILLION people. The U.S.A. is the 3rd most populous nation in the world. (only falling behind India and China).
No one really knows how many firearms are in private hands in the U.S.A. but one of the more credible research papers put the number at over 393 million guns in 2018. This is still only a best guess. We can look at the number of guns manufactured domestically plus the number of guns imported since 1968. We then add those numbers to what was believed to be in circulation before that, and come up with a baseline. It's not perfect but it's a start.
http://www.smallarmssurvey.org/filea...ms-Numbers.pdf
Since 2018, that number has been added to considerably. Manufacturing and importation alone is in the millions for the years after that study.
The sales of new guns in 2020 broke ALL records.
So when people start talking about bizarre conspiracy theories concerning ammunition and component shortages, take a moment to think about how big the numbers: 328 Million and 393 Million really are.