Al
The two most important operations in doing barrel work is chambering, and threading. Both like a nice heavy cutting oil that adds a free machining quality to the whole operation. Some are just not up to the task.
We have switched over to the Ridgid Dark Sulphurized oil, the kind they use in their threading machines. I have been doing this for 40 years, and the Ridgid is about the best we have used this side of the old Lard Based Oils that stunk to high heaven.
I won't even mention White Lead. For those that are old enough to have used it, they know that when mixed with lard based cutting oil, it was the best stuff ever.
Of course, for obvious reasons, it was out lawed. Amagine, using a known cancer causing agent with a medium that grows bacteria..........jackie