Do you have a data source for that? I won't get into the gun debate as it's pointless, but when I did a google search right now, the data I was able to find doesn't support your assertion.
1) STATES: here are the states with the most gun deaths / 100,000 people. None of them are known to have "stiff" gun laws, in fact, quite the opposite.
Gun violence in 2024 was highest in Mississippi, followed by Louisiana, New Mexico, Alabama, and Montana.
www.statista.com
2) CITIES: This is from 2021, but here are the cities with the highest gun violence. NYC is way down on the list. Chicago and Oakland are in the middle but most of the cities at the top are not known for strict gun laws (although I admit I don't know each major cities gun laws). Memphis consistently comes up as #1 on many lists and they don't have strict gun laws.
drexel.edu
Even if you look at total crime rate, I don't see the connection you are making (google cities with highest crime rate).
And if you look at murder rates, it doesn't show that either.
New Orleans, Louisiana, had higher murder rates in its home county than any other major city.
usafacts.org
What the data does show is that higher concentration of those living in poverty / higher rates of unemployment and areas that are more racially segregated have more gun violence. That makes sense to me.
Again, I'm not wading into the gun debate as there are a lot of factors at play here, but I'd like to see the data that supports "Stronger gun laws = Higher crime rates".