This comment made me curious so I looked up some data (sorry for the formatting, I don't know how to do it better):
Guns per 100 people
- Finland 2017: 32.49 (total of 1.79 million) [1]
- US 2017: 120.5 (total of 393 million) [2]
All gun deaths
- Finland 2017: 138 [1] (~77.09 deaths per million guns)
- US 2017: 39773 [2] (~101.2 deaths per million guns) <- A bit higher
Mean death rate per million in mass shootings, 2009-2015 [3]
- Finland: 0.132 <- A bit higher
- US: 0.089
[1] https://www.gunpolicy.org/firearms/region/finland
[2] https://www.gunpolicy.org/firearms/region/united-states
[3] https://worldpopulationreview.com/country-rankings/mass-shoo...
The data seems to suggest that the number of deaths and mass shootings sort of tracks with the number of guns, and that Finland isn't particularly better off "per gun".