I have made many many pins , both replacement and custom using old 1/4 socket extensions as its tool steel and very very hard . I wont go into my lathe process as I got picked on last time but it works .
I have used feeler gauge for flat springs but is very difficult to drill .
I have used a chunk of stainless steel boat prop to make a sear trip , stainless is just weird , likes its soft but hard as hell at the same time , maybe its tensil is low but has a hard surface ?
I have even used a exhaust valve to make a firing pin that could not be bought anywhere .
I want a small lathe but I fear the trouble I would get into If I had one and I damn sure dont need a mill