The rate dropped 38% in the US and 27% in the UK, which banned handguns in 1996.
https://www.macrotrends.net/countries/USA/united-states/murd...
https://www.macrotrends.net/countries/GBR/united-kingdom/mur...
*I would've used the most recent US number (2020), but I couldn't find that data for the UK to compare apples to apples.