I don't know what is so hard to understand. You do not, I repeat, DO NOT, have a constitutional guaranteed right to own a modern sporting rifle. Now, when the second amendment was a collective right based on the arming of a militia, you could make the argument that you did have a constitutional right to modern sporting rifles. A really good argument. But that ship sailed away with the judicial activism, and creationism, of Heller. Now the second amendment is an individual right based on self-protection. Do you need a modern sporting rifle for self-protection. Why no, no you don't. Not only can we tax modern sporting rifles, we can ban their production for private use, we can even ban owning them. Because that ban would not significantly "infringe" upon someone's ability to have another type of gun for self-defense
OK, so according to you, the government can outlaw Islam then because they still have the choice of another religion.
According to you, government can shut down the NY Times because you still have other news sources you can listen to.
Thing is it's not up to you why I want to own guns. And the Constitution says it's not up to the government