The 2nd amendment only applies to muskets
We’ll often hear anti-gun activists say or write in comments that the 2nd amendment only applies to muskets. There are many errors in this line of reasoning, the most common one offered is that a change in technology doesn’t change the underlying right. We tend to respond with analogies to the 1st amendment. Saying things like the 2nd amendment applies to modern small arms the same way the 1st amendment applies to radio, tv, and the internet. This is of course a legitimate defense but I don’t think it is our best one.
If the purpose 2nd amendment is to protect our right to keep and bear arms, and the purpose of keeping arms is to defend life liberty and property then it follows that any arm one bears for the purpose of defense is protected by the 2nd amendment.