Probably cold flow in that direction from the peening. Next time make a plug from steel to fit in the hammer slot. file it to a light (finger tight) press fit. You might want to drill it to hold it in place with an old hammer pin while you work the rails.... Of course, you know that you don't really need to peen to get accuracy. I know, I know....I still do it too sometimes.
[This message has been edited by BBBBill (edited 09-25-2001).]
[This message has been edited by BBBBill (edited 09-25-2001).]