I possess a 9m handgun and a 30 round mag so it is just as dangerous at close range in a way. Just like hammers their is a hammer made for every type of hammering. At very close range a 9mm handgun would be more dangerous tha. An AR at medium to long range, 50 yards to 300 yards an AR is the ideal solution. 300 yards to 1200 yards a bolt action rifle in 308 and up. 1200 to a mile or more is a specialized bolt action rifle with chamberings in 338 lapua and 50 BMG.
The plain truth is any gun or rifle is dangerous, in fact a hunting rifle in many ways is more dangerous than 223 AR as the round is bigger and designed to kill large animals. Their is nothing more dangerous than a man determined to kill another human and is willing to sacrifice himself in doing so. This man will find any way he can to do so, look at uk, mass stabings.
Perhaps we should look at our society and see why people are so misserable they will kill themselves in mass attacks,. I propose its wealth inequality, financial slavery, and a government that is not for the people.