Hey I got it I did make the notch skinnier but I also had to file the raised ridges on the sides of the mag as well.
I don't know how well it'll function but I'm glad I got to practice on a cheaper mag before I got one of the more expensive ones.
I would have rather used my dremel though I have a delicate touch with one and I could be more accurate in what I was doing.
Next time
:-)