This is the one that I have and use.
http://www.pipesandcigars.com/wolfmagcut.html a plastic shell with 2 sizes of cutters, one on each end. I paid $16 buy for $30 you can get the same thing with a metal shell.
http://www.pipesandcigars.com/womagcufme.html
Here is an example of what it can do with a larger RG, in this case a 52rg
I don't always punch but when I do this is the one I use.