Amassing guns does not mean amassing knowledge and training on how to properly use them. On a side note, the actual number is more like 1.2 guns per civilian, which is (terrifyingly) impressive.

Even if that number wouldn't be a simple average, it still doesn't mean each civilian has received proper training or is even fit for handling a gun, even though 72% have apparently at least once fired a gun in their lifetime - though that can literally mean they onced pulled the trigger on a hunting trip with dad at age 7, with him holding the gun.

Honestly, let me speak as an American as well: People shouldn't be handling guns at all.

Sources: https://www.pewresearch.org/social-trends/2017/06/22/the-demographics-of-gun-ownership/

https://www.smallarmssurvey.org/