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Old December 27, 2011, 01:46 AM   #1
TripHlx
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Metals used in firearms manufacture?

Hey guys, I have a question about the materials that are used in making a firearm. I have very little experience with metalurgy, but I do understand some of the basic concepts.

My question is, exactly what steel/other metal alloys are being used in guns today? Are there alloys specifically rated for use in firearms? Rated for specific calibers?

I know from some experience with knives and knifemaking that certain steels are only useful for certain projects, and that the heat treat is as important as the steel itself. Is this also true with firearms?

Could making a firearm at home be as simple as drawing up a design, milling the parts from a billlet, and slapping it all together after some finish work?

The reason I ask is because I have a few ideas for some simple but fun guns that I would like to try building from home.(To my knowledge, this is legal as long as certain rules are followed) I'm doing a lot of research, but thought I might come to you guys for some quick answers, just in case I'm getting in over my head here.

Thanks in advance for any info you guys can give me, and any areas of research you can suggest will be greatly appreciated!
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Old December 27, 2011, 04:01 AM   #2
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Like any other things choice of materials is important. In the past guns were for the most part steel and the type of steel depending on the part.Some were just low carbon steel , some were low carbon steel carburized .One alloy steel that has been associated with guns is 4140 . Heat treat is part of the choice.
The other common metal is aluminum . The newer material used are polymers
How the material is formed is another important choice . Machined, cast, and the newest MIM .
BTW it's spelled metallurgy !
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Old December 27, 2011, 04:11 AM   #3
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Oops, and I usually pride myself on my spelling. Oh well. Thanks for the info, I've been doing some more research since my post, but any other answers will be more than welcome!
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Old December 27, 2011, 08:11 AM   #4
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416 and 17-4PH are two stainless alloys I know are used. 4140 for carbon steel is the only thing I ever see mentioned. The metals used are not caliber specific. Heat treatment won't be caliber specific, but will be pressure level specific.
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Old December 27, 2011, 08:37 AM   #5
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Before you get into your home-built experiments, you might want to read up on the history of the Springfield 03, and why early production guns are considered unsafe . Poor steel and inconsistent heat treatment can give you a real headache.
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Old December 27, 2011, 09:35 AM   #6
Jim Watson
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The materials are better and there are commercial heat treating services that will let you build a stronger gun than case hardened mild steel.

Most guns are chrome moly, 4140 as said, plus 4150, 4340 and 4350 that I have heard of. The legendary Norinco is variously said to be made of a Oriental equivalent of a 5000 or 8000 series alloy steel,
If stainless, 416R and 17-4 PH.

Aluminum is usually 6061 T6 but Kimber uses a higher alloy.

Phil Lichtman once did an article on the materials he used for prototyping. He said one of the 8000 alloy steels, S7 tool steel, O-1 mild steel, and 1050 carbon steel covered all his gun parts. But he did have them heat treated.

You can have a finished part heat treated or you can get pre-hardened billet and accept the tooling wear. Some manufacturers do in order to avoid the risk of warpage from heat threatment of complex finished parts.

Frank DeHaas had a couple of falling block single shot designs suitable for DIY, you might read his books to see what material he recommended.
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Old December 27, 2011, 10:27 AM   #7
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If you want to do it at home, 4140 is the way to go. Carborizing a receiver is involved unless it is something low pressure. If you have access to a heat treating oven using 4140 is really cheap. The action is usually not as smooth, but it is one of the strongest materials to use. Some parts are 8620 which is like the best of both worlds, but it almost requires a professional heat treater to use it. Same for a lot of the other materials. They usually require a special oven to get proper results. Anyway, there are some strong guns out there made from 4140 that I know of, and others I suspect are.
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Old December 27, 2011, 01:05 PM   #8
James K
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"Could making a firearm at home be as simple as drawing up a design, milling the parts from a billlet, and slapping it all together after some finish work?"

Yep, that's all there is to it. I never understood why the gun companies insist on complicating things.

Jim
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Old December 27, 2011, 01:34 PM   #9
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Very good info here. As a tool & die maker for 30yrs , currently working in the aerospace field , I've worked with some common and unusual materials.

Some of the things that are considered for production are initial material cost. Some alloys simply cost much more than others.

Ease of machining , some materials are a real pain to machine. Machine time = $$$!

And when it comes to heat treat , we leave it to the pros and use a certified commercial heat treater. (Solar Atmospheres)

Distortion during heat treatment. Steels will shrink , expand , even become magnetic during heat treatment.

And every material has it's own heat treatment procedure , it's own critical temperature and soak time for hardening and tempering.

And there's the quench. Air , oil* , water , brine , certain atmosphere. *And by oil , I don't mean a bucket of old motor oil. There are specific oils (Houghton) meant for quenching at specific rates.

Each alloy has it's own protocol as to it's heat treatment set by the manufacturer.

When it comes to making guns at home , ya gotta do research , select the steels properly , and know hat yer doing when it comes to heat treatment. They don't call it critical temp for nothing. Not hot enough , it won't reach hardness throughout. To hot and ya can actually burn the metals molecular structure and end up with a bomb. Re; the low number 1903 Springfields.

Last edited by mkk41; December 27, 2011 at 01:44 PM.
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Old December 28, 2011, 02:08 AM   #10
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My father was chief engineer of 150 engineers and draftsmen for 40 years. He pounded on table tops and screamed in people's faces. They designed military vehicles and guns. My father has ~ 35 patents and is still a force to deal with.

He had a metallurgist on staff, Hank Hadley, that would ponder what steel alloy was best and research, but probably the project engineer would make the decision.

I recall my father saying about designing springs, 4140 closed and ground, and them some heat treat procedure.

I have been hacking off pieces of 4140 this week, designing and fabricating some barrel mounting parts, in my little hobby shop. Always keep coolant on that stuff when cutting it. If it gets hot, it ruins the tool, and makes a hard spot that will take carbide to cut through.
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Old December 28, 2011, 09:52 AM   #11
TripHlx
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This is exactly the kind of info I was hoping to hear from you guys. From what I'm gathering between you guys and other resources, I'm heading in the right direction so far, but have a ways to go before I even begin working on a material. Keep it coming guys, and thanks!
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Old December 28, 2011, 03:07 PM   #12
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Time is not the only factor to consider when machining is involved. When S&W first came out with the Model 60 (stainless version of the Chiefs Special), they ran into a whole bunch of trouble, saying that machine tools lasted barely 1/10 as long with the tough stainless steel as with carbon steel. That, folks, adds up to a lot of money! They stopped production for a year or so, and some people said there would be no more stainless steel guns! But S&W used the time to work with the tool makers on super hard tools that would machine stainless steel at reasonable cost and we know that stainless steel guns did survive.

Jim
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Old December 28, 2011, 05:02 PM   #13
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Yes Jim , early stainless alloys threw another monkey wrench in the works. But metalurgical research and technology solved them. Early stainless alloys had a tendency to gall unless plenty of certain lubricants were used. Especially parts that were investment cast. The early stainless autoloaders needed disimilar alloys in slide and frame to prevent this. But it all worked out.

Many people have a lot of wrong info about stainless. They are surprised that stainless steel knives and guns are magnetic and will rust. Most use 400series which hasa high carbon content , needed so they can be heat treated for strength and wear properties.

Similar problems were encountered with titanium alloys.
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Old January 2, 2012, 08:42 AM   #14
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I helped someone make a round shower fixture in my lathe with stainless.
I had sparks flying off the cut.

Lothar Walther stainless barrels have a reputation for requiring a different speed of cut, and getting a burr in the throat.

But Shilen stainless cuts like butter.
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Old January 2, 2012, 12:51 PM   #15
brickeyee
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Quote:
"Could making a firearm at home be as simple as drawing up a design, milling the parts from a billlet, and slapping it all together after some finish work?"
Wit till you need a barrel.

Turning ad threading it are the least of the work.
Even chambering is not that hard, but lath helps for accuracy.

Sine bar rifling machines have not been made in a long time.
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