I bought a cast hammer from Lodgewood for my Mississippi Rifle. I've ground off the casting sprue. What type of file does one use to fit the "square" (not) hole in the hammer to the tumbler? I have needle files but they are too fine. Secondly, how does one polish the hammer so that it is nice and bright? Should it be browned? This is a repop Bernardelli from the 1960's. Thank you.