As has been pointed out several times, and dishonestly snipped several times, the right to bear arms does not include the right to use them aggressively.
The right to bear arms implies the ABILITY to use them aggressively. This is very similar to the way a person's right to privacy implies the ability to hide evidence of crimes or commit criminal conspiracy.
The question before you is, at what point does the ability to use weapons aggressively outweigh the utility of the right to bear arms? For all PRACTICAL purposes, this can be quantified as: "As soon as gun-related homicides cause more death or injury than private gun ownership would otherwise have prevented."
In some cases, the tradeoff is pretty obvious: private ownership of machineguns would not have prevented the Las Vegas massacre, therefore private ownership of machineguns is not a practical extension of the right to bear arms.
Private ownership of semi-automatic rifles would not (and in fact, DID NOT) prevent the Sandy Hook massacre, and therefore private ownership of semi-automatic rifles is not a practical extension of the right to bear arms.
Concealed handguns are an ambiguous case, because police officers often use them as a deterrent, as do private citizens (store clerks, homeowners, etc) in self defense of home or property. On the other hand, handguns are BY FAR the most common means of homicide in this country, so without solid data it's very hard to tell if private ownership of handguns prevents more injuries or deaths than it causes.
Shotguns and hunting rifles are very rarely used in crimes; I saw a statistic (I can't find the source anymore) that bolt action rifles were used in exactly THREE homicides in all of 2015, while shotguns were involved in 27, the majority of which were self defense. If this is true, then rifles and shotguns would indeed prevent more deaths than they cause, on the whole.
I've seen it before, this weird argument that if you take Sane Citizen and give him a gun he automatically becomes a Slavering Psychopath, but if you take away that gun he reverts back to Sane Citizen.
That's not the argument, though. The argument is that there are certain times in every man's life -- conditions of stress or despair or rage or other form of transitive weirdness -- in which he should absolutely NOT have access to firearms. By the same token, there are also certain people who should, under NO conditions whatsoever, EVER be trusted to have access to firearms. The latter category is described under the umbrella term "mental health." But the Adam Lanzas and Steven Paddocks of the world are actually better examples of the former: deeply troubled but otherwise rational people who decide, for reasons known only to them, to do something terrible with guns.
You cannot guaranty that you will always be of sound mind, make rational decisions, exercise the best caution and self control at all times. You, who cannot know the future, certainly cannot guaranty that you will never ever use a firearm recklessly or irresponsibly or act out of anger, or fear, or despair, or under the influence of drugs or alcohol. There is no way you can guaranty any of that to anyone's satisfaction. There IS, however, a simple way I can guaranty that if you DO decide to do something terrible with a firearm, the amount of damage you can do will be relatively small. I can do this by limiting your access to firearms and/or restricting the type and number of weapons you are allowed to legally own. So that if one day you get pushed over the edge and snap, that you will not have the tools at your disposal to easily pull off a massacre.