Murders by type of weapon

From http://www.fbi.gov/about-us/cjis/ucr/crime-in-the-u.s/2011/crime-in-the-u.s.-2011/tables/table-20

Knives are used 5 times as much as rifles and body parts are used twice as much as rifles.
Rifles are 2.81% so why does the gun control debate focus on them?