Home Forums Hunting & Shooting Gunsmithing Black nitriding question

Came across this thread on the Custom Rifles and Wildcats subforum:

https://www.24hourcampfire.com/ubbt...15874818/nitriding-question#Post15874818

The subject of getting the last of the salts out of the receiver/barrel interface comes up and there is discussion about whether to remove the barrel from the receiver. I specifically asked H&M about this and was told that I needn't remove the barrel from the receiver. I'm guessing they came up with a way to get all of the residue out of the barrel/receiver threads? Or maybe I need to call them about it?

Scotta45-70 NOTING??? INSULATED??????????????????????????????????????????????????????????????????

https://www.americanrifle.com/shop/product/mausingfield-bolt-action-2

About halfway down the page:

SAFETY AND TESTING

Read this section! You might actually find it interesting and entertaining.

...

An action needs to have a margin of safety to resist the dangerously high loads resulting from misuse. The margin of safety stems from both proper design and proper heat-treatment of the steel from which the action is made. Therefore, the Mausingfield action must never be subjected to temperatures above 400°F (204°C) for any reason, because doing so will significantly weaken it and compromise its safety margin. The Mausingfield must not be subjected to high-temperature surface treatments such as ferritic nitrocarburizing or salt-bath nitriding, because such treatments are conducted at temperatures ranging from 900-1200° F (480-650° C). These treatments are marketed under several trade names, including Nitrotec®, Tufftride®, Tenifer®, QPQ®, and Melonite®. While these finishes might be suitable for some firearms, they are not suitable for the Mausingfield and may not be suitable for other bolt actions either.

AND... the last paragraph on THE SAME PAGE that quote came from:


SURFACE TREATMENT

The Mausingfield is supplied with a salt bath nitride surface finish to harden and blacken its surfaces. The resulting finish effectively resists corrosion and reduces friction thus enhancing the smoothness of the action. The bolt head is coated with diamond-like carbon (DLC) surface finish. DLC is an extremely hard and wear-resistant layer on the exterior surfaces. This will reduce the friction between moving parts, thereby enhancing the smoothness of the action. DLC treated surfaces hold oil which enables them to resist corrosion reasonably well.

Check it out: https://www.americanrifle.com/shop/product/mausingfield-bolt-action-2

Whether or not salt bath nitride treatment is a good idea depends entirely on the specific alloy used, the geometry of the part, and the material heat treat condition prior to SBN.

Mausingfield changed their material used in the action and has since then offered salt-bath nitrided finish. The paragraph you quoted from above is old information from the first gen Mausingfield that they forgot to remove from the website. The current Mausingfield Gen 2 is suitable for salt bath nitriding and is offered with it directly from ARC.

Gas nitriding is a much lower temp process, and is usually a physical vapor deposition (PVD) process that has "line of sight" application, meaning that it won't deposit the coating on internal surfaces deep within narrow cavities or bores, as opposed to salt-bath nitriding that is submerged in a high temp cyanide salts bath, affecting all surfaces of the part exposed to the bath. Gas nitriding is also a deposited coating (albeit an extremely thin one) rather than a case hardening surface transformation like salt-bath nitriding, and it can thus be applied to a wider range of materials. Depending on the chemistry, gas nitriding can be black, and if so, it looks similar to salt-bath nitriding, but a wider range of colors and sheens are possible with gas nitriding.

Edited to add: DLC (diamond-like carbon) is an example of a type of gas nitriding/PVD. TiN (titanium nitride) is another.