Scalia -
"Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose: For example, concealed weapons prohibitions have been upheld under the Amendment or state analogues. The Court's opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms. Miller's holding that the sorts of weapons protected are those "in common use at the time" finds support in the historical tradition of prohibiting the carrying of dangerous and unusual weapons."
I feel like you guys are having the standard debate where each side is fighting for their position, when the positions don't align with one another. You're both right.
You can own a gun. Which gun you own can be regulated. The important words are "in common use at the time". It's the sole reason why a handgun ban can't be passed, but an assault weapon ban could be.
Regardless, the argument is this. If owning a weapon is your right, is it unconstitutional to require the person who owns it to have knowledge and training in how to use, store, and operate the weapon. Should the weapon be licensed? Should the people who sell weapons have to go through the same verification processes as a dealer?
Keep in mind we have in place many other instances where age requirements, licencing restrictions, certifications are required before being allowed to use or operate a multitude of things. Why is it such a burden on your freedom to apply the same logic towards something that's general purpose is to kill something?
I could really care less that responsible gun owners use whatever weapon they want. The key word is "RESPONSIBLE". How best do you ensure this. The argument can be made that a majority of weapons used in crimes are obtained illegally and can't be traced.
How are all these weapons even getting on the streets? Gun shows seem to be one way, selling weapons to individuals on a personal level is another. I'm relatively sure we can find ways to limit the accessibility of weapons used for illegal means without infringing on your right to own an AR-15.
I simply hope you can make a better argument than, I want a gun, and I want it now.