With all the concern about assault weapons since the federal ban sunset in 2004, it is interesting to see what a small share of murders are committed with any type of rifle and how even that share has fallen over time. The percentage of firearm murders with rifles was 4.8% prior to the ban starting in September 1994, 4.9% from 1995 to 2004 when the ban was in effect, and just 3.6% after that (3.9% if you look at just the first ten years after the an ended). The data is from the FBI UCR reports.
The average rate of firearm murders committed with rifles after the assault weapons ban was statistically significantly less than the rate during the ban at the 0.0001 percent level for a two-tailed t-test. There was no statistically significant difference in rates for the period before the ban with the assault weapon ban period.
There are similar drops over time if one looks at the share of total murders committed with rifles.