I have a good friend of over 30 years who is an engineering physicist. He has worked on projects that are currently in space and now works in what he jokingly refers to as "the military/industrial complex" (think missiles). His engineering skills are almost legendary in his speciality field.

Over the Christmas holidays we got together and I showed him the 5" pre-27 (made in 1954) I posted a picture of here. He admired it quite a bit and sent me the following engineering rundown on the weapons of that era. I thought his comments about Smith & Wesson would be of interest here.


"After seeing your S&W 357 I started thinking about the state of American manufacturing at the time the weapon was made. American metallurgy and quality of manufacture were nearly at their height in the 1950s. During the 1950s and to a lesser extent in the 1960s, American metallurgy produced a remarkable variety of high performance materials in both quality and quantity. Your new S&W is an example of this. Another example is the use of an advanced aluminum alloy, 75 ST (now known as 7075) in the frame of the Colt Commander. This was the first aluminum alloy with the yield strength of steel; unfortunately its fatigue properties later turned out to be inferior of those of steel. Incidentally, 75 ST was quite important in postwar aviation, enabling the development of high performance jets and very long range aircraft. The Stellite liner for the M60 machinegun barrel was developed about this time. With a Stellite lined barrel an M60 can fire the “basic load” of ammunition carried by an infantry unit without a barrel change, at least at normal rates of fire. Even when used in sustained fire, with a Stellite liner the barrel is changed after three to four times more rounds than with a comparable conventional barrel, from say for the German MG-34. Finally, the M-14 receiver used 8620H steel, and is perhaps at the very pinnacle of US firearms metallurgy. Proof of this is both the difficulty of manufacture; H&R in particular had great trouble making the receiver, and the incredible longevity of the receiver. It is claimed that the M-14 receiver service life is around 400,000 rounds or more; again the receiver service life of a contemporary weapon such as the FAL is around 60,000 rounds. Some advanced metallurgy did not get into the firearms world, which is unfortunate. The maraging steels offer incredible performance and are relatively easy to work, however these metals are not used anywhere in the firearms industry. By 1960 the range of tool steels available in the US was incredible; there was an alloy for almost any cutting application. In addition specialty alloys were common for certain applications. At this time designers could get industrial development of alloys for certain applications; today it is necessary to design to an ever shrinking list of alloys.

Your S&W 357 Magnum is made of a 41 series steel, probably 4130. This steel offers a good combination of high strength and toughness. The 41 series steels are still the best for firearms use; the M-16 barrel is made of 4150 (and there is a MIL-STD for this alloy for barrel use). The frame was made as a “closed die” forging to near net shape. A fairly elaborate heat treatment is necessary after forging to produce the optimum properties for the steel. Final machining was by broaching. Broaching is almost unknown today, but was common fifty years ago. The broach is a pyramid shaped cutting tool, which is oscillated along its long axis. The tool is slowly forced through the aperture in the frame to produce the rectangular aperture for the cylinder. S&W probably has more experience with broaching than any other company. Incidentally, the cost of broaching machine tools is one reason that revolvers are not common today. The combination of high quality steel, forging, heat treating, and broaching produces a very high performance product. Today S&W makes frames from free machining steels; it often uses type 416 stainless in its products. This type of stainless steel is easy to machine, and does not require heat treatment. However the properties of 416 are inferior to that of 41 series steels, as users of the Model 66 quickly learned! In the 1950s S&W could use forging shops that were located nearby; today the part must travel to the Midwest or elsewhere for this operation. Ruger uses investment casting to produce revolver frames; again the properties of an investment casting are inferior to those of a forging, no matter what the advocates of the process may say. (About a year ago I saw US Army mortar barrel forgings stacked up like logs at Scot Forge in Illinois; the Army did try an investment cast mortar barrel without success.)"


I got his permission to post this but he asked that his name and contact info be left out so I'm respecting his privacy.

Dave

__________________
RSVN '69-'71
PCSD (Ret)

Thanks for sharing. That was very interesting. I'm glad he said that investment casting is weaker no matter how you look at it. People on the internet can be so ignorant.

that has to be one of the most interesting things I have seen all week, thank you for sharing!

Thanks for posting, very informative.

Rod

Very interesting posting, I wish S&W would take heed and make their M&P slides from better steel. Mine's full of blemishes from worn cutters, maybe better steel would cut better.

IMO, the steel is fully capable of being machined smoothly, but S&W may not change out the cutting bits frequently enough for maintaining an optimum finish.

What he said is technically true, but remember: Rugers usually outlast Smiths. Maybe because they're beefier. And their designs are more modern.

And M-66's endure better than M-19's. Stainless alloys have their merit, especially if the gun is often carried in damp conditions.

T-Star

A very interesting statement. I have been reading "Ruger and his guns" and he was very high on investment casting as most of his products use some of this. I always thought S&W's did the best of any manufacturer, although I have several Rugers. Jeff

One point he is accurate with: "today it is necessary to design to an ever shrinking list of alloys." Crucible Powdered metals recently went bankrupt; a major supplier of the highest grades of composite carbide metals.

Thanks for posting this interesting essay.

Do Rugers really outlast Smiths? I've put a lot of mileage on some Smiths.

Very interesting. Makes me feel even better about my older S&W wheelies!

Rugers have a reputation for going longer than Smiths without needing gunsmithing.

Both will last a long time with reasonable use and proper care.

Metallurgically, Colt has had the best rep. But their designs are flawed. A Colt typically doesn't hold its cylinder timing nearly as well as either S&W's or Rugers. Their latest designs, from the Trooper III-on use a different timng system, which is far superior to their old style. But the triggers are abrupt in action after a long pull, and the overall lines of the guns just aren't too pleasant. I'm not surprised that they didn't sell well.

T-Star

My friend followed up his original e-mail with the following:


"I've heard the arguments about the strength of stainless steel and castings
many times before. In discussing material properties it is important to
understand which properties are important. In selecting a material for use
in a firearm yield strength, fatigue strength, fracture toughness and wear
are all important. In addition corrosion resistance is sometimes important.
Unfortunately there are a lot of misconceptions about metallurgy, even with
professional engineers.

There is a common mistake made in selecting or talking about materials which
is called "the single property fallacy." (I've given several talks at
professional conferences about this issue. I have a somewhat embarrassing
reputation now as a materials expert; some of my papers are now standard
references in certain areas.) Often materials are selected based on a
single important property such as yield strength, without considering other
factors such as cost, fracture, or ease of machining.

A good example is found in the stainless steel alloys. One outstanding
stainless steel is 17-4 PH, which offers exceptional strength and superb
resistance to corrosion. It can also be investment cast. These attributes
are offset by the need to heat treat the alloy for strength. During heat
treating the part typically distorts by about 5%; and after heat treating
the part is so hard that machining to correct the distortion is extremely
difficult. Further, like most stainless steel alloys, when 17-4 PH is run
in contact with another stainless steel, it is subject to a severe type of
wear called "galling" at very low contact pressure. The original AMT
Hardballer prototype pistol used investment cast 17-4 PH in its slide; the
alloy was changed almost immediately after early failures! AMT had good
company; I've seen a major aerospace company make the same mistake - and now
teach engineers about this issue.

Now, S&W uses type 416 stainless steel in its handguns. Type 416 is one of
the easiest stainless steels to machine, with a machinability rating of 85%
in comparison with carbon steel. In addition, this stainless steel can be
investment cast, typically to near-net-shape to a tolerance of around 0.005
inch. Since minimal machining is necessary after investment casting,
production cost is greatly reduced in comparison with parts made by closed
die forging. As cast, and with heat treatment, the yield strength of 416 is
about 55 ksi (1 ksi = 1000 psi); in comparison the strength of 4130 when
investment cast and after heat treatment starts at 75 ksi. With proper heat
treatment the strength of 4130 can be as high as 160 ksi; which is
considerably above that of 416. S&W uses 416 to keep manufacturing cost
low, while offering some improved resistance to corrosion; this steel is
inferior in all other respects to the 41 series low carbon steels. Note
that I am comparing different steels when investment cast; when forged 4130
is even more superior.

The arguments about casting versus forging with respect to strength ignore
the physics of the two processes, as well as actual tests performed on the
alloys. When cast, a part cools from the surface to the interior in a
non-linear way (typically the interior cooling rate lags that of the surface
in accordance with an exponential relationship). Grain size is governed by
cooling rate, so grain size in a casting varies from its surface to
interior. This differentiation in grain size produces a change in physical
properties, most notably with respect to both strength and resistance to
fracture. In contrast, forging produces a high level of homogeneity in
grain size. Also, forging allows control of the direction of the grains, so
that they can follow the contours of the part. This can be exploited to
further increase strength."


Again, I found the above very interesting and informative. Hope the members here do too.

Dave

__________________
RSVN '69-'71
PCSD (Ret)

Perhaps they went bankrupt however they were bought out by ATI. See this thread if you wish: http://www.investquest.com/iq/a/ati/.../ati102609.pdf

This is very informative. Thank you for taking time to post this info.

Charlie

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SWCA # 2294

This would make a great sticky in the gunsmithing section.

This subject is fascinating to me; thank you for posting.

Interesting, but I wonder at:
"In the 1950s S&W could use forging shops that were located nearby; today the part must travel to the Midwest or elsewhere for this operation"

It has not been all that long that we read gunzine articles about S&W doing contract forging for other companies. When did they start, stop, resume, and stop again doing their own forging? Or were the gunzines just making it all up?


Some barrel makers warn against using type 416 stainless for small diameter rifle barrels to be taken hunting in cold climates. One 1970s pistolsmith lamented that his barrelmaker had gone from type 410 to type 416 and reduced the safety margin for his admittedly hot loads.

Great thread, I would love to hear his opinions / comparisons on the scandium lightweights.

Very interesting, thank your friend for taking the time writing this up for our knowledge.

Fascinating subject and write-up. Thanks,

Jerry

Very interesting. I wonder what his thougts are on scandium and titanium alloys used by S&W.

__________________
NRA Life Member

+1 Me too

An informative post indeed. To me, the significant comment is that American metallurgy reached its peak in the 60s. The evolution of metallurgy has accelerated since then, sadly most developments have been overseas.

siiiiiiiiiiiiiiiiiiiiiiiiii

Very interesting and informative.

I too would like his input regarding Scandium frames and the two-piece barrels in use today.


Cat

__________________
Think for yourself.

I originally posted this here (Hand Ejectors) because of the info contained about 1950s materials and machining. This latest e-mail is probably better suited to the more modern era but several here asked about scandium so I'll continue to post here. I asked in the context of S&Ws light weight 1911s as the original alloy Commander was my favorite off duty and plain clothes weapon. I cracked 3 Commander frames just shooting them so I wanted to know if adding scandium to aluminum would make a more durable Commander. Here is my friend's response:


"I did some research into the properties of aluminum-scandium alloys over the weekend. I quickly learned, as stated in one journal article, that "information on the properties of aluminum-scandium alloys is scanty." Further, many of the aluminum-scandium alloys are proprietary, which means that information on composition is not available. Usually properties of proprietary materials are provided by the manufacturer, rather than a neutral third party, and must be cautiously evaluated. Finally, S&W does not specify what aluminum-scandium alloys are used in its products. So there is some room for differences in opinion regarding the suitability of aluminum-scandium alloys in firearms.

One paper did show an improvement in both ultimate tensile and yield strength for a 7010-T6 aluminum alloy after addition of scandium. Ultimate tensile increased about 7%, and yield strength about 4%. This increase is in keeping with the patent claims on the alloying of aluminum with scandium. Easton, one of the companies offering aluminum-scandium bicycle frames, does not claim any increase in strength with its aluminum-scandium alloys in comparison with conventional materials.

However, tensile and yield strength are not the only properties of importance. Even more important in determining service life is the fatigue strength of the material. Unlike steels, aluminum alloys do not have an endurance limit at which the lifetime is indefinite. Typically fatigue is evaluated by a combination of factors such as allowable strength for a given number of cycles and fracture toughness. Typical fatigue strengths for aluminum alloys with 0.25 to 0.3 % Sc added are between 150 to 160 MPa (22 to 23 ksi) at 10 million cycles. This is identical to fatigue strengths for comparable 50 series alloys, and is inferior to the fatigue strength of 70 series alloys. Some studies suggest reduced fatigue strengths for certain aluminum-scandium alloys in comparison with similar conventional aluminum alloys.

Fracture toughness is another critical material parameter for fatigue life. This material property is related to the stress required to propagate a crack of a given size. The higher the fracture toughness, the larger the crack that is tolerable for a given stress, or alternately, the higher the stress for a certain crack size. Adding Sc to a 7010 alloy reduced fracture toughness to around 60% of the conventional alloy. This is a serious and significant reduction, implying that the allowable stress must be reduced by a comparable amount. Again, this trend is confirmed by other work cited in the literature. In some cases the fracture toughness of aluminum alloys with Sc added was only about 10% of that of comprable conventional alloys. This is a serious drawback in a material intended for a firearm.

I did not find any information on wear, friction characteristics and machinability of aluminum-scandium alloys.

The limited information available on aluminum-scandium alloys suggests that the primary advantages are the ability to weld higher strength alloys, and a possible improvement in corrosion resistance. There may be a small increase in both ultimate tensile and yield strength, but this is offset by a dramatic reduction in fracture toughness. At best fatigue strength is comparable with conventional alloys. To quote one source: "The average values of fatigue life parameters appear within a range of magnitudes common for many engineering Al-alloys produced by conventional techniques." (ref: A. Vinogradov et al, "Fatigue life of fine-grain Al-Mg-Sc alloys produced by equal-channel angular pressing," Matl. Sci. Eng. A, A346, 318 (2003)). I think that use of the aluminum-scandium alloys in firearms is an example of the "single property fallacy," in that the emphasis is on the small increase in ultimate tensile and yield strengths without considering the full range of applicable properties.

So I would not expect a 1911 with an aluminum-scandium frame to show any better service life than a Colt Commander with a forged 7075 frame. It would not surprise me if the aluminum-scandium frame actually proved to have a shorter service life, since the fatigue properties of certain of these alloys are inferior to those of conventional materials. For a revolver frame the aluminum-scandium alloys may allow a small decrease in weight, although this is likely to be offset by a reduced service life (an extremely lightweight 357 Magnum probably will not be shot much, so this is an acceptable trade).

Again, I may change my opinion if better data becomes available. At the moment I think that aluminum-scandium for firearms is mostly marketing."


When asking my friend a question, you need to be prepared for the answer. It's usually longer, more detailed and blunt than sometimes is expected or desired (LOL). In the 30+ years I've known him I have never found him to be materially wrong or prone to give bad info.

Dave

__________________
RSVN '69-'71
PCSD (Ret)

Very, very interesting. Thanks for answer. I actually understood it! That's a credit to his writting skills!


Cat

__________________
Think for yourself.

Interesting! I have an S&W Sc Commander. His comments, while well researched and presented, are caveated by the proprietary nature of S&W's alloy. Thus, it remains a possibility that S&W has addressed the Fracture Toughness issue and this is simply not available in the literature. I guess I'll cling to that. Maybe Clint Smith's idea of buying several of anything he really likes is a sound practice. thanks for the effort DaveT.

DaveT,

You mentioned that you've killed three Colt Commanders by shooting them. Care you to describe their lives? Round types, round count, etc?

Thanks.


Cat

__________________
Think for yourself.

First one cracked at the dust cover on both sides at around 2500 rounds, most a handload duplicating 230 Ball. Second cracked at the slide stop cut out, the dust cover on one side and showed a hairline crack at the slide stop hole itself (it had been electroless nickeled) after approx 5000 rounds. The heaviest load shot in it was Fed HydraShok 230s (not +P). The third one cracked on both sides at the mag release and under the thumb safety. It digested the most rounds, about 6500, none of which were heavier than non +P factory.

Dave

__________________
RSVN '69-'71
PCSD (Ret)

Very good information and agrees with everything I have heard about materials. In the oilfield, 4130 is common for good reason. Various Inconel grades (high nickel alloys) are used for non-magnetic, corrosion-resistant applications. Galling of 17-4PH is also well known in the oilfield. Some of these assembled 17-4PH parts (especially large diameter helical threads) seemed welded together when you tried to loosen them. Small bits of material would ball up and fill the space in the thread locking it up.

There was a forum thread about N-frame heat treating a while back. This materials information adds to that. Steel has many mechanical properties (beyond hardness or yield strength) with trade-offs between them. Fracture toughness is hugely important.

Interesting post. Thanks for sharing.

Thanks for the informative reply DaveT.

Makes me wonder about the life span of my aluminum framed Shorty .45.


Cat

__________________
Think for yourself.

DaveT, This is a great thread! Dare you ask your friend about MIM parts?

__________________
NRA Life Member

Me too! I have 4 aluminum-framed .45 autos (Sig,kimber,para, & Smith (with Sc)). At most, one of them may have a little over a thousand rounds and I don't shoot +P. Also, thanks again for your efforts DaveT.

My friend cracked the frame of an alloy framed Para Ord some years ago. We discussed alloy frames then as it was about the time I cracked my second or third Commander. His take was that the forged aluminum frames could be expected to digest from 5,000-7,000 rounds. He indorsed the idea that alloy framed guns were intended more for carry than digesting thousands of rounds for years. There is some design consideration there too. The 1911 frame was initially designed to be made of steel. It takes quite a beating which work hardens aluminum. A gun like a SIG, with a purpose built/designed alloy frame will probably hold up longer.

That's all paraphrasing his thoughts, but we discussed this subject (his and my cracked frames) over and over for several years. I'm confident about this being his take on the subject.

Dave

__________________
RSVN '69-'71
PCSD (Ret)

I've only got two lightweights-a 317 and a 337. After reading what your friend had to say, I'm knida glad.
Were the 1970-80 era blued N frames made of that 4130 ?

__________________
Forum consigliere

Please, maybe in the gunsmithing section

Thank you

Very well presented, informative post.

rayb

__________________
"cumplo pero no obedezco"

DaveT,

Your friends take on the dreaded MIM parts would be interesting.


Cat

__________________
Think for yourself.

A thread I saved and read from time to time. Very interesting and I own a 1954 Pre 27 also. I try to memorize it so I sound smart when arguing at the range. Sofar Ive butchered it up pretty badly during battles. Mabye I should just print it and slap a copy on the table when being accosted.

Broaching...Now there is a process that you don't hear much about today. I worked at Remington years ago and have to say that they also had decades of experience with broaching. It was fascinating watching those machines carve out the interior surfaces of the Remington Model 700 receivers. They used broaching for many other applications at the factory also. As impressive was the level of skill and precision of the machinists (or tool and die guys) that worked in the tool shop keeping the broach cutters sharp and tuned.

Some may not be aware that Ruger runs a sizable business in making precision investment castings of all kinds for customers that have nothing to do with the gun trade.

The skill lies with the tool designer and the toolmaker. Properly set-up, the broaching operation is more or less "push button" simple for the machinist.

The comments about the Aluminum/Scandium-alloy are interesting. Its use in a specific product, for instance, the frame of the revolver, likely requires a good deal of actual testing to know whether the addition of the material has merit or is just a flash in the pan. Presumably, S&W has done that testing and knows whether it serves a purpose, if so, to what extent (cost effective), or whether it is a sales technique that is basically useless from an engineering point of view. Generalizing about the topic may not be very helpful in terms of revolver manufacturing.

It might be nice if manufacturers would give us the benefit of their testing, but if they did, likely a lot of products would never be offered for sale. I have had Commanders all my life and am very fond of them (even though one has cracked), but if someone had told me to expect them to crack after, say, 4000-rounds, I probably never would have bought one. The frame of the SIG 220 seems even more fragile to me. On the other hand, I have seen reports of 220s going 30,000 rounds without failure. In all, there are a lot of pieces in this puzzle and material is just one of them. Nothing tells the story like testing of the actual product.

I actually visited their facility in NH in 1980 when we were sourcing parts for the "NEW" GE CF6-80 engine.

We used a hand-full of investment cast parts.

Back at about the same time I was an engineer working for a company which designed and manufactured various types of downhole oil tools. Pine Tree Castings (Ruger) made many components for us. They made it very clear that even though we were good customers, there would be no "special deals" on Ruger guns.

For those of us not familiar with broaching, this is pretty good:
http://m.youtube.com/watch?v=7n1r5XfVkyk
This too:

http://m.youtube.com/watch?v=rjckF0-VeGI

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Halfway and one more step

Looking at the stress issue with the aluminum-scandium alloys makes me think that maybe the issues with barrel tightening and frame cracking is related to the stress tolerance of the alloy used. I think that's a serious problem, as proper barrel mounting is not an option.

I will also note, however, that most shooters do not put a lot of rounds downrange. The higher volume shooting of the last decade or so was much less common 50 years ago, and I have seen the statistic claiming that most folks put 600 rounds downrange in a gun's lifetime. If correct, then a 2000 round service life in a gun that one carries a lot and shoots little (like a snubby in its best role, as a BUG) is no big deal most of the time.

I have had the same experience with exercise equipment. Most made for home use becomes a coat rack soon after purchase, so if you are a big ape who beats hell out of the gear as I sometimes do, the typical entry level stuff will die a quick death.

__________________
NHI, 10-8.

This is drifting a bit but on the heels of Doug M.'s comments, probably most (or at least a lot) of us can remember Elmer Keith writing about his skepticism of the Airweight Chief, which he subsequently debunked by means of his own field testing - with his own handloads, no less!

At that time he wrote that the big wigs at S&W stated the intended service life of the gun was 2500 rounds, IIRC. He satisfied himself that the provided test gun (as in one test gun) held up nicely for that. Nowadays, the way some people write about "training" you would imagine they go through 2500 rounds in a year or less.

In EK's opinion, that kind of service life for the airweight gun seemed a reasonable trade off for the convenience, and he recommended practicing with your steel gun and carrying the airweight. I know a few of us who did just that.

From doing work on an N1K2 Shiden Kai I found that the first use of the 7000 series aluminum alloys was in Japan. Used in the main spar webbing of the Zero, and later in the Shiden kai, etc. SDCH was their marking on the parts so used. So, in this case, it was the Americans who followed in the Japanese footsteps...OT, but good ideas are where you find them.

Back on topic, I tend to not keep aluminum framed pistols or revolvers very long! Not if they get shot or handled very much. Once the anodizing is worn through I reckon that's enough. That layer of hard oxide is what prevents most of the wear. Never mind the lack of a lower endurance limit on "fatigue" life.

Practically speaking, it's why that heavy hunk of 940 rides around with me rather than one of the airweights.

Your friend is a rare engineer that not only knows his stuff, but can communicate effectively, Dave T. I can barely string a couple of sentences together...I'd rather do the math or fabricate something. He!!, most MEs can barely spell, and that's the ones with real aerospace jobs!