A friend of mine with a "LOT" of machining experience told me that for firearm applications, (especially anything with a bearing surface) I should avoid using leaded steel (11XX) and use 10XX.
NS
That is good advice, the free machining steels have terrible toughness and that is the last thing you want in a weapon containing high pressures applied at extremely high strain rates.
As a side note, 4140 is generally considered very easy to machine. What are you guys comparing it to? 7075 is decent, too. At least it is hard enough to chip off properly. 6061 is terrible to machine, all gummy and hard on tools.
A small, fiddly part like that firing pin out of S/S using HSS tools requires a LOT of patience. Nice work, NS. You even got a decent surface finish on it!
Mark




















































