The issue that you hard liner no restriction guys don't get is there are mechanisms to repeal the second (or any other) amendment. If the line becomes so hard as to loose public support you will loose everything by the amendment being repealed. It has to be flexible enough to withstand the pressures against it.
Here's how I see it. My rights are like money. I start out with my full rights intact, $100. Over the years, muggers have got me over and over again, whittling away at it a little at a time, taking what they are not entitled to, so now I'm down to about $60.
I don't really understand the argument that it makes sense to freely give them another cent they are not entitled to, in the hopes they will let me have the rest of my money they are not entitled to.