There's no source about firearm-related murder has increased after Clinton's gun control law expired, there's some factors that cause firearm-related murder to increase, such as US was in recession in early 2000's and make black market so more bigger and bigger, it has been became change the society in 2000's and CA has strict gun control but most of gangs and future gun owners are favor into black market to get guns and their gun control law isn't 100% effective but rather to make black market so bigger.
I don't believe in gun control law that harms to good citizens who want to be gun owners, including skyrocket of price for firearm sales.