First, my opponent has chosen to take issue with my claim that AR-15s have been the firearm of choice in many mass shootings in America.
My previous source indicated that of the shootings in the last 35 years, at least 13 have involved the use of an AR-15. Have mass shootings become so commonplace in American society that at least 13 heinous acts of human violence within 35 years cannot be considered many?
Regardless of how my opponent has attempted to diminish the AR-15s role in mass shootings, this does not change the fact that yes, the AR-15 has been involved in mass shootings and yes, they were effective in those mass shootings. Rarity should not be a factor when determining whether something should be banned or not, only the impact when used.
Consider for example instruments of biological warfare which are and were very rarely applied. These types of weapons were banned due to their horrific nature, but it is also true that guns have killed and maimed far more than they ever will. My opponents logic suggests that instruments of biological warfare should therefore not have been banned which is of course absurd.
An example such as the Las Vegas shooting, the deadliest mass shooting event in American history in which AR-15s were used to great effect in combination with bump stocks should be considered no different. It, and the other examples of mass shootings demonstrate the vicious efficiency in which the AR-15 can cut through life. This is no different to the horrors brought by biological agents in resolution, only in application. And hence AR-15s should be banned.
Secondly, my opponent has asserted that the ability to kill is not a negative. Indeed he claims that it is a positive, that guns should be effective at their job and hence is not a reason for banning them, in particular the AR-15.
To this, I say that my opponent has wrongly interpreted my words. I did not argue that AR-15s should be banned because they are efficient and effective at what they do. I merely noted that they possessed those qualities.
Finally my opponent has asserted again that there are many weapons that are more powerful than the AR-15.
Again, I do not disagree with this. But this is just not an argument against banning the AR-15. This is an argument that there are other weapons just as bad. However, my opponent has not argued that either weapon is good and should therefore not be banned. Thus, because the AR-15 has a proven track record of death, the conclusion can only be that both guns must be banned. However for the purposes of this debate topic, just the AR-15 suffices.
A few points of note before the end however. My opponent claims that no one speaks of banning guns other than the AR-15. This is false. Much discussion has been made over various assault weapon bans 
. This includes not only the AR-15, but others of its class. Finally my opponent claims that people only wish AR-15s to be banned because they look deadly. Apart from this being unsubstantiated, I find there to be a much more reasonable explanation. AR-15s have a proven and consistent track record of murder.