A couple years ago I had a mini 14 re-barreled with a Douglas SS varmit barrel. Douglas Barrels INC. also sent along the following statement, some may find it of interest.
Dear Customer:
This is a STAINLESS STEEL rifle barrel, made of type 416 straight chrome stainless steel. It will not blue by ordinary methods, or any other that I know of unless, the barrel is plated with some metal that will blue the ordinary way. This stainless contains aobut 14% chromium, but does not contain any nickel. It might not be completely rust proof under extreme conditions of salt, or strong acids. The use of this steel by me, is primarily for the purpose of extending barrel life, which we believe it will do, and not for its stainless charactieristics.
This barrel also is a HEAT TREATED stainless, running around 28 to 30 Rockwell "C," before it is ULTRARIFLED and then stress relieved after rifling, to around 25 Rc. in hardness. Now here is a matter you must watch with any stainless barrel. A GOOD STAINLESS BARREL CAN BE DAMAGED BY A POOR CLEANING ROD!!!! Stainless steel, while in many instances actually harder by hardness test, DOES NOT HAVE THE SCRATCH RESISTANCE, that a chrome-moly barrel will have of equal hardness. This scratch resistance quality, therefore, that NO STAINLESS BARREL HAS ON AN EQUAL WITH A CHROME-MOLY BARREL, is a matter of utmost importance, if your good stainless barrel is to be kept undamaged. Always inspect your cleaning rods for the presence of burrs, bends, or other damage that might abrade or scratch the inside of your stainless barrel. If you rod is a jointed one, be sure that the joints screw up well, and that there are no burrs at these points. NEVER CLEAN ANY BARREL FROM THE MUZZLE END, if it can be cleaned at all from the breech end.
If you use a wire bristle brush in a stainless barrel, do so with care, so see that the brush fits well on the rod, without bends, or burrs that might scratch the inside of the barrel. REMEMBER, a stainless barrel can actually register harder than a chrome-moly barrel, but be much less SCRATCH RESISTANT.
If you doubt all this, or have never heard of if before, ask your favorite metallurgist about it.
Douglas Barrels, Inc.