Quote Originally Posted by K.L. Davis View Post
Well, I would say that which is "easier" (between chromo and 416) has a lot to do with the experience and preference of the machine operator, as well as what type of machine is being used -- but yes, many will say that they prefer to work with 416 vice 4150...

...but that is not what I said.

I maybe should make it clearer though: Metals are (loosely) rated with a "machinability rating" -- and the base for this rating (1.0) is free machining carbon steel, alloys can be much lower on the scale, right off the top of my head, I think that 41XX is down around .50-.60 and 416R is well above that in the .80s?

But, as this is a primer, I just thought I would make the general statement that 416 machines nearly as well as carbon steel, rather than say that it has a rating of .85 (or whatever)... then we are off on free machining additives and resulfurization, chip control, inclusions and break points, and then the door is opened to the dreaded sulfur stringers and then night of the living sulfur stringers and then...

Kino, are we not on the same page? Based on your own machinability numbers, 416 is clearly the easier of the two (meaning 416 compared to chromoly) to machine at similar hardness. Barrels aren't made from low carbon free machining steel so it really isn't relevant to compare it to 416R.

For those that don't know...

The American Iron and Steel Institute ran tests for machinability using AISI B1112 at 160 Brinell (a free machining low carbon steel) being turned at 180 surface feet and compared it to other materials. Its performance (set at 100%) is the basis for the ratings of other metals. Those materials with a rating of less than 100% are more difficult to machine. Those with a rating of over 100% are easier to machine.

4140/4150 chromoly steel has a machinability rating of approximately .32 to .52 depending on hardness. But 416 is a free machining martensitic stainless and has a rating of anywhere from .24 to .88 depending on hardness.

For comparison, Inconel is around .12, 7075 aluminum runs anywhere from approximately 3.2 to 4.8.