Seems the 2nd amendment in some ways mimics the UK laws that every able bodied man over the age of 7 and under the age of 60 be required to own a long bow and practice with it regularly (under the observance of the local clergy). Since at that time any able bodied man could be called up in defense of the realm.

Similarly, the early US states foresaw the need to be able to call up every able bodied man to serve in the defense of the state (hence the militia inclusion). This militia was not part of the paid military, those being effectively the national guard of today. The militia was an irregular force of civilians, who needed to supply their own weapons, but (being well regulated) those weapons needed to be of the same type as the regular state military, so that ammunition supplies could be drawn from a common supply. Hence everybody carried the cutting edge weapon of the day. Of course going by this theory one could charge that the 2nd amendment is a requirement for everyone to be able to stand in the defense of the state with their own rifle and maybe handgun, using the same caliber ammunition as the state reserve - since the state needs to be able to call up a militia for its defense.

Unlike the US, the British militia requirement for owning and practicing with a long bow (the cutting edge military weapon at the time the law was invested), was probably revoked in 1960 and definitely revoked in 1986. And of course much easier to revoke as it was a law and not an enshrined right.

In a similar way it could be argued that the 2nd amendment requiring men to own a firearm for the event of them being called up to defend the state is an anachronism, as warfare has progressed past a few rows of men standing at opposite ends of a field shooting in the general direction of "each other". We now have high tech aviation and artillery that requires a lot of specialized training and practice in addition to other hardware that to be honest makes a civilian militia more of a liability than a boon. But then it's more difficult to revoke a right than it is to revoke a law.
I used to think it was terrible that life was unfair. Then I thought what if life were fair and all of the terrible things that happen came because we really deserved them? Now I take comfort in the general unfairness and hostility of the universe.