when I started in the vice i had about an inch sticking out. it seemed to just flake off some of the brass but no real peening. I then put it down farther and made sure the end of it was pressed up against a metal rod so it had something to support it. It was out .2 inches then. I ended up bending that one.
my problem was i wasn't sure how to hold/secure the rod when doing the initial peen. i tried it a bunch of different ways, including just holding it in my hand.
I have a 4 oz peening hammer. i am thinking that some of you might be using 12 or 16 oz peening hammers. a heavier hammer is going to be a lot easier to peen with, i have to hit it pretty hard to get it to peen since it is so light.
Now I am putting it into a hole I drilled in my small anvil from tandy leather. the hole is 1/16" and about an inch deep. I try to have 1/8 an inch sticking out to peen, that way there isn't any room for the rod to bend.