Adding guns probably doesn’t increase crime rate. It does the mass murder rate. It is precisely gun crime that I abhor. Thus I'm opposed to their availability.
You should be able to easily show that rural USA with it's murder rate on part with Europe is definitely not the place where all our guns are... oh wait...
My claim is that the mass murder rate, the rate at which we have mass killings in the U.S. would go down if buying/selling guns were illegal.