I used the following data in this post. The population came from the US census, the rest came from the FBI.
Total population: 318,900,000
Number of deaths: 2,596,993
Firearm murder: 8,124
Rifle used: 248
This is a pie chart showing the population of the USA and the number of people who die every year in the USA.
The blue is the population of the USA (~ 320 million) and the orange is the number of people who died in 2014 (2.59 million)
Now, here's another pie chart.
Here you have that sliver above expanded. Again, the whole represents that sliver, so this is all of the murders in 2014. Blue is non-firearm, orange and gray represent firearm murder, and gray is murders where a rifle was used... All 248 of them.
Now, the math:
Of the 318,900,000 or so people in the USA, 248 of them were killed by a rifle.
For comparison, in 2012 (the latest year for which I could readily find data), 722 people were killed in bicycle accidents in the US (almost three times as many as killed by rifles.)
So tell me again how banning the AR-15 is going to make any significant impact on death in the US.