Craft Gunmaking, No compromises, No corners cut, EVER

Sunday, October 28, 2018

Some More Mythbusting

If you ever find yourself at a gathering of collectors of American doubles and need a conversation starter, the subject of triggerguards and nitre bluing should make for a lively exchange.  There are those who correctly state that the nitre method was the finish used and, invariably, there is a self-styled guru in the opposite camp. There are only two factory-original finishes found on the triggerguards and other peripheral parts of a classic American doublegun: nitre blue or casehardening.
The assertion that the only color that the nitre methods yields is the bright "peacock" or "fire" blue is patently incorrect, and serves only to illustrate ignorance on the subject.   The nitre method can yield colors anywhere from a light straw color to black.  I routinely blacken parts using the method, and I do mean black.  This is without adding any chemicals to the nitre bath.  The idea that the finish is too "delicate" or "short lived" to be used on a triggerguard is nonsense as well.

Prior to 1937, the hot caustic black oxide (commonly known as "hot bluing") method did not exist.  The Mauser firm was the first to use it and by 1938-9 it had made its way to America.

The methods that existed for blackening steel prior to the above-mentioned "hot blue" were rust bluing, nitre bluing, charcoal bluing, heat bluing, Carbona bluing (also known as machine bluing, among various others) and paint (that's not a joke, Winchester finished their stainless steel barrels with a product called "black Japan" which, effectively, was paint).

Where "classic-era" American doubles are concerned, no American maker EVER rust blued any parts EXCEPT barrels, neither did the British.  The British used the labor-intensive charcoal method to blacken the furniture on their best-quality guns and the nitre method on their lesser, production guns.  Only the Germanic makers ever rust blued everything (they seemingly had quite an affinity for the process).  If I had a buck for every so-called "restoration" (there's that word again) of an American double that I've seen with rust-blued triggerguards and forend irons, I'd be able to retire to the Bahamas.
I repeat, all American doublegun makers used rust blue for barrels ONLY.  Any peripheral parts such as triggerguards, toplevers and forend irons that were not color case hardened were in fact, nitre blued.  I know this to be true because the finish is called out on the parts drawings of some American manufacturers.  There is no reason to believe that all American makers would not use the exact same finishing methods, especially when that method is perfectly suited to mass-production by semi-skilled labor.  I have seen actual original examples of the finish on these parts and I can duplicate them perfectly, as can quite a few others.

Savage was an early adopter of the hot caustic method which greatly sped up the finish process.
The only Fox guns that did not have nitre blued furniture are the very latest production, Savage-built guns. In fact, the very last Utica-made guns may be encountered with hot-caustic blued barrels because Savage started brazing the entire barrel assembly, ribs, forend lug and all, specifically so that the time-consuming rust-blue process could be eliminated entirely.  This practice apparently continued on with the production of the 311 and Fox Model B (which itself was a tarted-up 311).

Speaking of Fox guns, there are times that I wish that Michael Macintosh had never written that book.  As a biography, I can find no fault because I know nothing of Ansley Fox's life, but the book does contain technical inaccuracies regarding the gun itself. 
 Things like the Sterlingworth pin guns being made from surplus PAC frames (which is not possible) and the existence of Chromox frames.  All Fox frames were made of SAE 1020, this is proven by the material callouts on the actual drawings of the frame forgings.  This includes all Philadelphia-era drawings and the Utica-era drawings.

The drawings, #D264 (dated 01/28/1910), #D302 (dated 07/25/1911), #F1 (dated 05/24/1938 Savage) and #F201 (dated 06/31/1938 Savage) all call out the same material specification and that specification is SAE 1020.  How do I know this?  I have photocopies of the drawings.  

The exception to the above are the New Britain Fox guns.  Those frames are made from 8620, which is a Chrome/Nickel/Manganese alloy with the same carbon content as 1020.  It has a much higher yield and ultimate strength than 1020 and is meant to be carburized (case hardened) like most other low-carbon steels.  The assumption that modern break-action guns use "4140" in their frames is also incorrect and seems to be rooted in the notion that 4140 is some sort of magical "gun steel" that is universally used in firearms production.  I blame this on gun-rag writers that (for the most part) know less about guns than their readers and toss this number into an article in order to sound credible.  The use of 4140 is nowhere near as widespread in the gun industry as many people believe.

Macintosh's assertion that a "Chromox" frame can be identified by how "shiny" it gets when worn is hogwash of the highest order.  The late frames' wear to a brighter finish is entirely due to the cyanide carburizing process that replaced the bone-charcoal carburizing process (coincidentally at the same time that the Chromox frames were supposedly introduced).  The cyanide process yielded a much harder surface than the previous method and a harder surface will naturally be brighter as it's worn from handling. 
"Chromox" was a name that Fox's catalog copywriters came up with for a particular barrel steel.   The fact that a catalog copy writer stated that the frames were also made from the same material means nothing.  It's called advertising.

He also stated that the early Sterlingworth "pin" frames were made from leftover P.A.C. frames, which is physically impossible.  There is, in fact, evidence that the P.A.C. guns were not even made in Philly, but that's a story for another post.  Suffice it for now to say that the P.A.C. frames (and forend irons) may well have come from the same forgings as those of another well-known maker.

A comparison of Fox "pin" Sterlingworth and P.A.C. frames: clearly neither was, nor could have been, made from the other. 

An example of nitre blued parts that are neither "peacock" nor "fire" blue in color.  The triggerguard, trigger, barrel selector and the toplever spindle screw (just ahead of the guard) are all nitre blued.
How do I know?  Because I'm the one that finished the parts (and the rest of the gun).

1 comment:

  1. Dewey,

    As always, I enjoy your posts. Please keep on myth busting and enlightening us.