If you don't use a good sulfur cutting oil, you won't get that great smoke and smell! It's kinda like the old Hoppes9 in a gun cabinet.
That takes me back to the first machine shop I worked in and some thoughts for
skeetlee,
We used sulfur based cutting oils for lots of our work but we also had a big bucket of sulfur additive we could add some with. It was a big ol'bucket like you might see in a cowboy movie hanging off a wagon for greasing the axles. It was about the same consistency anyway. Big stick in it and everything.
I ask my boss why it worked. He said he thought it was such a reactive element that it clung to some materials like steel and made it easier for the cutter to get a grip to cut, OR it clung and made the chips slide easier. Anyway it seemed to help on steel. (Like barrel steel.)
It will make brass and copper tarnish if it gets on them. For that we used either something we called "Red" oil or Hangsterfer's.
http://www.hangsterfers.com/products/cutting-oils/
Hangsterfer's is a chlorine based oil. It was some of the best working and smelling of all the cutting oils. I suppose chlorine is very reactive and clings like the sulfur. ? Hangsterfer's is also a good all around cutting oil. Running it could save you cleaning out a machine to change coolants when you wanted to run different materials.
Another coolant I've used over the years that stood out was a water soluble coolant. It was made by Blaser. Maybe Blasocut. Water soluble coolant is very thin and pumps easy. The water is very good at cooling things. Blaser made the best water soluble oil I've tried but it falls short for some machining situations.
http://www.blaser.com/index.cfm?type=land&navid=48&subid=450&land=us
Keep in mind I've mostly been working in Swiss Screw machine job shops. Not as a Gunsmith.
I think a person getting familiar with machining would need a good selection of coolants and cutting oils. All the types seem to have their place.
One thing you don't want to try is using lube oil as cutting oil. When I was starting out in machine shops I was drilling a hole on a manual machine. I ran out of my little tin of coolant and spotted an oil can within reach. I squirted some of it in my drilled hole and went back to drilling and burned up my drill like right now. It turns out that the oil molecules they use in cutting oil and in lube oil are way different.
Which makes me drift off and remember that was one of the nice things about running a machine with water soluble. You could skim off some of the old lube oil that would end up in it.
