Paulo Products in Nashville TN can harden firearms components using gas nitriding. They have an FFL so guns can be shipped to them for work. Their process leaves the metal a satin gray color them tell me. I haven't seen it yet. I'm planning to send a single shot action as soon as engraving has been completed. I spoke to Richard Janeway at 615-345-4913. I don't know what it will cost. I'm looking at this process as an alternative to casehardening to avoid parts warping.
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
"Salt bath" nitriding is the process that leaves a finish quit similar to rust blue. I have never had anything "gas nitride'" treated, so I'd have to take Vol717s' word for the 'gray' color. My understanding is that any of the nitriding process only 'hardens' to a microns deep, not .010 to .015".
Posts: 719 | Location: fly over America, also known as Oklahoma | Registered: 02 June 2013
Originally posted by dpcd: But I have had 25 receivers hardened any Blanchards and never had one warp. Why change now?
Agreed! Nitride treatment has its place, but I feel it's not a good substitute for case hardening low carbon steel. I had Blanchards re-carburize a batch of 12 Mauser '98s early last spring. No warpage to speak of in any of 'um.
Posts: 719 | Location: fly over America, also known as Oklahoma | Registered: 02 June 2013
If what Silvers said is true...(.010-.014 hardening depth)....Well that's in the ball park of Blanchards specs, though one can specify deeper AND at what CR.
There must be some advantage to nitriding that escapes me...
What I read about the process,,not recommended for parts subject top shock...i.e. gears
So...still leaves me somewhat curious about advantage.
Posts: 3675 | Location: Phone: (253) 535-0066 / (253) 230-5599, Address: PO Box 822 Spanaway WA 98387 | www.customgunandrifle.com | Registered: 16 April 2013
The advantage of gas nitriding is minimal warping. How many of you gunsmiths have had to knock a receiver back into shape after heat treatment? The gas nitriding process is done at about 1000 F. It produces a surface "white" layer that is very hard, and underneath that, a somewhat softer layer, akin in hardness to charcoal casehardening. Specifically, according to a Paulo metallurgist, " For prehard 4140, a typical range for white layer depth would be 0.0002-0.001. There is also an area of increased hardness just beneath the surface similar to case hardened materials. Typical case depths are in the 0.015-0.020” range." Now I just need to see what the surface looks like for myself. I have two of Martin Hagn's single shot rifles in .223 and .30/06. Martin Hagn does not recommend casehardening his actions, especially the mini action in .223. I have seen pictures of a Hagn action that had a silver appearance after nitriding, and also one that was very black. Both were built by Ralf Martini.
I just talked to H&M (blacknitriding). Their hardness layer is between .001 and .008" thick and their finish is a shiny black. They have an FFL and do regular hot bluing, however as well.
By the way, does anyone know if Blanchards has an FFL?
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
Originally posted by dpcd: No he said nitriding is NOT the .010-.012 that we need for real case hardening. He said microns. Whatever that is.
1 micron is 1/1000th of a millimeter. 1 millimeter is the equivalent of .0394 inches. I have used H&M , MMI TruTech in the past. I currently use Controlled Thermal Technologies in Phoenix (CTT). I primarily have rifle barrels nitride treated. The process leaves a slick, hard surface (68-72C) with good wear resistance. It is used primarily on alloy and stainless steels. I have had punch press dies nitride treated, also. There has been no change in accuracy in the barrels I have had treated. If there was a warpage/deflection issue, it seems it'd be evident when used on rifle barrels. It substantially increases barrel life for barrels chambered for those "barrel burners'. The engineer at CTT is where I got the 'microns'. He (the engineer) also said that salt bath nitride is not a substitute for traditional heat treatment in most instances, that it's an "add-on" to enhance the operational characteristics and longevity of the 'part'. Lots of 'parts' need to be hard and tuff, the "tuff" come with proper heat treatment. Blanchards has a FFL, that's why they can do Mauser actions (that, and they've done enough research to know what steel a Mauser '98 is made of). Most alloy steels with a carbon content above .35% don't respond well to case hardening. Also, the elements used in the alloy "get in the way" if case hardened. 8620 color case hardens very well, 4140 does not. A simple google search shows a long list of products that are routinely nitride treated to enhance wear characteristics,,, including gears and some machinegun barrels. Some of the current custom bolt action makers have their bolts nitride treated and their actions can be treated as an option, also.https://www.metallurgyfordummies.com/nitriding-how-it-works.html
Posts: 719 | Location: fly over America, also known as Oklahoma | Registered: 02 June 2013
So what is the answer? Will it work on 1020 (Mauser) steel? We aren't taking about 4140; that doesn't need a surface harness; plenty of carbon it already. (I actually knew what a micron was)
Posts: 17442 | Location: USA | Registered: 02 August 2009
Originally posted by dpcd: But I have had 25 receivers hardened any Blanchards and never had one warp. Why change now?
Maybe because the steel the actions Vol717 has are not of low carbon steel and not suitable for case hardening? Medium and high carbon alloy steels don't case harden well, they 'through harden'.
Posts: 719 | Location: fly over America, also known as Oklahoma | Registered: 02 June 2013
That is exactly what I said above. My take away is that this process is totally unsuitable for Mausers. Since the reason we have them re-heat treated is because they are, or we suspect they might be, too soft. As in Pre WW1 made ones. If they already had a sufficient hardness, adding a superficial layer would be a waste of time and money.
Posts: 17442 | Location: USA | Registered: 02 August 2009
I believe that gas nitriding will be best for my guns. I'll wind up with silver receivers snd rust blued barrels. Small parts like buttplate, grip cap and escutcheons will be casehardened.
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
I'm confused; are you saying that a pre WW1 98 will be made good, after nitriding? I thought I read above that the hardness depth was super thin. I thought....
Posts: 17442 | Location: USA | Registered: 02 August 2009
This maybe helpful, it seems to be the process being discussed on this thread. From the point of view of corrosion proofing I'm a fan as years ago I spilt car battery acid all over my Miroku U/O shotgun. In fact the gun lay in the acid on a soaked foam pad until I reached my destination and discovered the mishap in the back of my pickup. The barrels needed re-bluing however the receiver looked buggered with a white powdery corrosion look all over. Nothing to loose so I lightly wiped over the receiver with fine steel wool and CRC 5-56 (WD40 equivalent) and the finish came up just like new with not a blemish to be seen. That occurred over 30 years ago and to this day the nitrided receiver has retained it's nice shiny silver look and remained corrosion proof.
From the Browning website;
What is Salt Bath Ferritic Nitrocarburizing? Browning shotguns with a "Silver Nitride" receiver utilize a proprietary process that is known among those who create metal finishes as salt bath ferritic nitrocarburizing. Over and unders made at our Miroku factory use a product with a trade name of Tufftride. The process leaves the receiver and other steel components with a bright, silver color while at the same time improving the finish and surface integrity in three ways:.
Greatly improving scuffing resistance Improving fatigue properties Increasing corrosion resistance. One major additional benefit is that while the process is improving the finish it induces very little shape distortion during the hardening process. This is very important to a finely fitted Browning over and under shotgun.
Getting Technical - Controlled Liquid Ionic Nitriding (CLIN) A more technical description is provided by the company who owns the process and can be helpful if you are looking for more a more detailed answer. Controlled Liquid Ionic Nitriding (CLIN) is the family name of different nitriding / nitrocarburizing processes which are well known under various tradenames. CLIN (controlled liquid ionic nitriding) treatment can be used in a temperature range from 480 °C to 630 °C and enriches the surface of ferrous materials with nitrogen as well as small amounts of carbon. CLIN salt bath nitriding greatly enhances properties like:
Wear resistance Fatigue strength Corrosion protection Cosmetic appeal Compared to coating or heat treatment processes CLIN salt bath nitriding offers numerous advantages.
Posts: 3944 | Location: Rolleston, Christchurch, New Zealand | Registered: 03 August 2009
Right; it's a finish; not a surface hardening process; at least not enough for a soft Mauser. At least that is what I always thought but now are guys saying they want to use it for that purpose?
Posts: 17442 | Location: USA | Registered: 02 August 2009
Thanks Eagle...really some good information. So....bottom line: Would any of these nitriding treatments ALONE be suitable for a ...like dcpd asks...for a WW I Mauser?... or how about the 09 I just recently discussed...with lug set back?
Posts: 3675 | Location: Phone: (253) 535-0066 / (253) 230-5599, Address: PO Box 822 Spanaway WA 98387 | www.customgunandrifle.com | Registered: 16 April 2013
Originally posted by dpcd: Right; it's a finish; not a surface hardening process; at least not enough for a soft Mauser. At least that is what I always thought but now are guys saying they want to use it for that purpose?
Browning does refer to it as a hardening process and if it provides wear resistance and fatigue strength it must use hardness to do this.
Posts: 3944 | Location: Rolleston, Christchurch, New Zealand | Registered: 03 August 2009
Originally posted by Duane Wiebe (CG&R): Thanks Eagle...really some good information. So....bottom line: Would any of these nitriding treatments ALONE be suitable for a ...like dcpd asks...for a WW I Mauser?... or how about the 09 I just recently discussed...with lug set back?
What causes lug set back - From what I gather it is usually high pressure loadings and then is it from a hammering action or scuffing wear as the bolt lugs rotate against their receiver seats to open? I think it is the latter action and I imagine a nitride surface hardening treatment such as used by Browning/Miroku would be suffice for a soft Mauser. Only one way to know, try it I suppose. Does sound like a good treatment system in that it does not affect the tolerances of a finished firearm and there is no warp factor.
Posts: 3944 | Location: Rolleston, Christchurch, New Zealand | Registered: 03 August 2009
Call one of that companies that provides this service and talk to the engineer. Ask him if nitriding is suitable for a a low carbon steel case hardened receiver. Those who I have talked to about nitriding have been very forthcoming with information.
Posts: 719 | Location: fly over America, also known as Oklahoma | Registered: 02 June 2013
No it does not sound like a good idea for a low carbon steel, soft receiver. The case depth is way too thin. Now, sending a receiver already properly case hardened sounds like a waste of time and money, to me. Again, Browning/Miroku does not use low carbon steel so the comparison with a Mauser is invalid. Lug set back is caused by lack of case hardening on a low carbon receiver. With anything more than the original 7.65 ammo; doesn't have to be high pressure. 30-06 will do it. Alloy steel (4140) receivers are tough and do not need to be hard to work. Yes, a call to them will reveal the truth and I will do that Mañana.
Posts: 17442 | Location: USA | Registered: 02 August 2009
I just personally spoke at length, with an Engineer from Paulo. BLUF: Gas Nitriding Process is wholly unsuitable for a Mauser, or any other receiver, in which the parent heat treatment is insufficient. I explained to him the history and current uses of Mauser receivers. We discussed the DWM made, pre WW1 ones which are sometimes lacking in hardness and case depth. He explained that his process is a superficial layer of hard steel, which is for wear reduction and smoothness; not for resisting shock loading. That is what the original heat treatment is for. He was also shocked to learn that the Mausers are made from 1018 or equivalent material, and were case hardened with bone charcoal. And other methods later, but were still reliant on that process to function correctly. He said, his process would proceed a very hard thin layer, but would need to be hardened first. He also said that most of the steel he processes is modern alloys and they come to him pre hardened. So. If you send him a soft receiver, it will come back to you with a thin layer of hardness, but will not be suitable for any use other than what it was before you sent it. We agreed that there would be no point in having his process done on a case hardened part. Only softer, alloy steels which do not rely on case hardening for their usefulness.
Posts: 17442 | Location: USA | Registered: 02 August 2009
Certainly no problem getting the information from the source.
For modern alloy steels that have already been heat treated, that you want a higher surface hardness, gas nitriding is a great option.
As a side note, I received the booklets from the printer and started shipping them yesterday. Your booklet(s) will go out in the next day or two and you'll have some more info on the original heat treating processes and some analysis of receivers.
Nathaniel Myers Myers Arms LLC nathaniel@myersarms.com www.myersarms.com Follow us on Instagram and YouTube
I buy Mauser actions, parts, micrometers, tools, calipers, etc. Specifically looking for pre-WWII Mauser tools.
Posts: 1527 | Location: Ohio | Registered: 06 June 2010
Originally posted by dpcd: I just personally spoke at length, with an Engineer from Paulo. BLUF: Gas Nitriding Process is wholly unsuitable for a Mauser, or any other receiver, in which the parent heat treatment is insufficient. I explained to him the history and current uses of Mauser receivers. We discussed the DWM made, pre WW1 ones which are sometimes lacking in hardness and case depth. He explained that his process is a superficial layer of hard steel, which is for wear reduction and smoothness; not for resisting shock loading. That is what the original heat treatment is for. He was also shocked to learn that the Mausers are made from 1018 or equivalent material, and were case hardened with bone charcoal. And other methods later, but were still reliant on that process to function correctly. He said, his process would proceed a very hard thin layer, but would need to be hardened first. He also said that most of the steel he processes is modern alloys and they come to him pre hardened. So. If you send him a soft receiver, it will come back to you with a thin layer of hardness, but will not be suitable for any use other than what it was before you sent it. We agreed that there would be no point in having his process done on a case hardened part. Only softer, alloy steels which do not rely on case hardening for their usefulness.
That's exactly right. For modern alloys only. I had the same conversation (might have been with the same engineer) a few years ago.
My Mauser M03 is factory nitrided. Badass is all I can say.
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Want to make just about anything work better? Keep the government as far away from it as possible, then step back and behold the wonderment and goodness.
Paulo shipped the parts back today. The order was "file hard", somewhere in the 60s, they said. The color is a light gray. Cost $570 for action, receiver, buttplate, lever and 4-5 small parts.
This process is Probably of no use to soft low carbon Mauser fans, but I'm thrilled.
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
The gun was received, the rest of the parts finished and reassembled. The finish is a dark gray. I would prefer a lighter color like French gray but that doesn't last. I have rubbed it off my shotgun from just carrying it. We will see how it holds up to use. I will get it back this week and post photos.
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
looks like that finish leaves a fair bit scale and is not terribly uniform. I think I prefer gently aged or removed colors myself. I did both of these guns long ago, colors eased off with a soft cloth and rottenstone using BLO as a lubricant.
I could do that I suppose, but it is file hard. Might take a bit of work. I'm building a .30/06 on a medium frame so I may try easing the finish on that one.
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Posts: 2184 | Location: Tennessee | Registered: 18 February 2007
