In Part One of this series, we talked about how the MIM process works, and in Part Two, we discussed the pros and cons of manufacturing products with MIM methods. In this next installment, we’re going to explore Smith & Wesson’s experience with transitioning to MIM production, and take a look at some of the engineering improvements that MIM allowed them to make to their famous line of revolvers.
By the 1990s, Smith & Wesson’s manufacturing operations were due for a shakeup. The manufacturing technologies, techniques and processes which had served them well for so many years were starting to show their age, and some changes were necessary to guarantee efficiency, profitability, and consistent, quality production in the future.
To figure out the next steps, the company conducted a survey of available technologies and manufacturing processes, to see if there was any potential to improve pistol and revolver production at Smith & Wesson. The Springfield, Massachusetts company had a mature operation, that was already nearing its 150th anniversary, and they could have just kept doing what they were already doing, but it was good stewardship to see if there was any room for improvement.
Their largest competitor in the revolver market was Ruger, who had been quite successful building a business around investment casting. Ruger not only built quality guns from parts that were largely made from castings, they had also migrated into supporting other industries with their Pine Tree Castings operation, which allowed them to apply their casting expertise to other endeavors.1 Through Pine Tree Castings, Ruger manufactured products for companies in the architectural hardware, power tools, sporting goods, medical, marine, and other industries, so there was good reason for Smith & Wesson to consider casting as a viable option.
There were complications which made casting a bad fit for Smith & Wesson, though. Every process has its own pluses and minuses, its own problems to deal with, and while Ruger had successfully navigated those waters, it wasn’t going to be easy for Smith & Wesson to do the same.
The Smith & Wesson revolver frames, for example, didn’t lend themselves to casting. You can get a very strong and durable frame from casting, as Ruger does, but it comes at the expense of the frame being a little thicker. The Smith & Wesson frames featured thinner walls, and used less material in certain high-stress areas, than equivalent Ruger frames, because they were designed around forging and machining processes. Those processes allowed Smith & Wesson to get the requisite strength in a thinner profile, and if Smith & Wesson was going to start casting their frames, instead of forging them, they would have to completely redesign the guns. The guns would have to be enlarged to accommodate the casting process, and that was simply a non-starter. Not only would it have been expensive to do so, it would have been unacceptable to their customer base to make the guns bigger and heavier.
Casting the smaller parts was technically feasible, but would have required an investment that would have netted very little, if any, return over Smith & Wesson’s current practices of machining the parts from forgings and raw stock, so it didn’t seem a financially viable undertaking.
Other companies, like Colt and Remington, had previously flirted with compressed powdered metal technology, to make small parts for their guns. In this operation, extreme pressure is used to compress powdered metal, which is then heated to sinter and solidify the material.
Colt, for example, made good use of the process for many of the internal parts in the Mark III series of revolvers (the .38 caliber Metropolitan Mk III, the .357 caliber Lawman Mk III, and the .357 caliber Trooper Mk III), which had been completely redesigned by Dick Baker. Baker’s action was a radical departure from the standard Colt pattern, and improved on the traditional Colt V-Spring, but the compressed powdered metal parts weren’t always seen as an improvement.2
Gunsmiths who tried to file or polish these compressed metal parts were dismayed to discover the material didn’t act like other metals, and sometimes crumbled away, once you started working on them. Additionally, there were reports of fatigue and failure with the compressed powdered metal parts, with hammer spurs breaking off during firing, and the like.
These complaints are rooted in the fact that compressed powdered metal parts only achieve 75-93% density (as compared to 96-100% for MIM), and also suffer from high levels of porosity. The lower density and higher porosity, compared to a forged or MIM product, makes for a less robust metal that is unsuitable for use in certain, high-stress applications.
An additional problem with compressed powdered metals, is that the process only works well enough to make simple, “2-D” parts. You cannot make parts with complex, raised shapes, or with cavities, holes, and recesses. Remington, for example, was unable to press out parts with holes for pins and screws, which had to be drilled and tapped later on, after the part came out of the oven. The technology could be useful in certain applications, but it was ill-suited for the complex parts that Smith & Wesson needed to manufacture for their revolvers.
A MIM Solution
The new kid on the block, metal injection molding (MIM), offered a lot of promise though, and the Smith & Wesson Revolver Engineering team was immediately attracted to its possibilities.
As we’ve previously discussed, MIM offers great potential for companies looking to make small, complex parts that require little-to-no machining. While the MIM process requires a lot of work up front to set up, once the molds, formula and process have been established, you can economically produce a high volume of very consistent, high-quality parts if you have a disciplined manufacturing process.
To explore MIM solutions, the Revolver Engineering team made contact with several companies that were in the MIM business. One of these was Advanced Forming Technology (AFT), now called ARC Colorado Inc. (ARC), a part of ARC Group Worldwide.
The team made several visits to ARC, with S&W metallurgist Jim Grochmal, PhD, serving as the “eyes and ears” for the company. Jim carefully dissected and examined sample parts made by ARC, and determined they were of high quality and excellent consistency. The S&W Revolver Engineering team thought ARC had a good process in place already, and felt that they could make a better-quality gun with MIM parts produced by ARC, so they went back to Springfield and sold the idea to upper management.
Management agreed with the recommendation, and Smith & Wesson made the commitment to move to MIM for a lot of the small parts in their firearms. Because of their expertise in forging and machining, it made more sense to continue making frames, cylinders, barrels, and other major parts in house, but Smith & Wesson would contract with ARC for parts like rebound slides, hammers, triggers, sights, and cylinder stops which could be improved by making them with MIM. In the transfer to MIM, Smith & Wesson eventually switched 54 components in their pistol and revolver lines over to MIM production.
Smith & Wesson also partnered with Parmatech, in Petaluma, California, to produce some larger MIM parts for their guns. With ARC handling the small parts, and Parmatech making the bigger ones, a new era of manufacturing at Smith & Wesson was well on its way.3
From the very start, Smith & Wesson worked closely with the vendors, in a “share key” operation, to develop the unique formulas that would produce parts with the desired characteristics. While ARC and Parmatech were already experienced MIM houses, with good MIM feedstock recipes and tight processes that delivered consistent shrinkage, Smith & Wesson wanted to use their own special blends of metal powders, to get parts with the strength, ductility, and durability they wanted.
This added time to the schedule, but it was worth the extra effort. It took ARC about six to twelve months, for example, to learn about working with the new formula and work out all the production bugs, but they were able to perfect the manufacturing process with the new mix and deliver exactly what Smith & Wesson wanted.
The Revolver Engineering team was prepared to reject the ARC and Parmatech samples early on, and look elsewhere, if they weren’t better than the parts that Smith & Wesson had been manufacturing for themselves. Fortunately, they were very pleased with the quality and consistency of the ARC and Paramtech products, and were glad to enter into long-term relationships with the vendors.
As happy as they were to outsource a significant portion of the small parts production to ARC and Parmatech, Smith & Wesson still wasn’t willing to subcontract the manufacture of the major components that were machined from forgings or billets. Smith & Wesson had developed quite an expertise in building parts like frames and cylinders, and wanted to retain that production in-house. It had been hard, at first, for the company to make the transition to machining stainless steel in the 1970s, but by the 1990s they were experts at it, and there was nobody else they would have preferred to do the job.
So, we’ve talked about some of the components that are now made via MIM, but how do the new parts differ from the old ones?
RevolverGuy’s sources advise that the MIM parts have maintained better tolerances than the old ones and are much stronger than the old ones, too. While they may not be as attractive to some customers, they’re a lot tougher, are improved in their design, and will offer better service life.
Take the new MIM hammers, for example. Retired Smith & Wesson Manufacturing Engineer Norm Spencer (of L-Frame fame) explains there’s a misconception that the old hammers were forged steel parts, but they weren’t . . . at least not for a long time. Smith & Wesson used to forge these until the 1950s, but the process for making them changed, and the company switched to punching them from flat stock with a press. The punched parts would be drilled for the stud and pin holes, then put in a press to swedge the thumb pad to the proper dimension. The thumb pad would be knurled, and the entire part case-hardened.
“The material had to be soft, to facilitate all the punching and swedging,” said Norm. “We had to use low carbon, 1020 or 1018 steel, soft stuff, for ductility.” The case-hardening process later added carbon to the steel, to harden the surface of the part, but the core remained soft.
In contrast, the MIM hammer is much more robust, much harder, all the way through to the center. With the old hammer design, it wasn’t uncommon for the Warranty Department to get a gun returned with the hammer spur snapped off, but that hasn’t really been a problem with the stronger MIM part.
On the Edge
It appears that the critical surfaces on the MIM hammers also hold up better, due to their consistency and harder material.
In particular, the surface that engages with the sear holds up much better on the MIM hammer, because it’s near perfect—it’s hard and it has the proper tolerance. Whereas the old hammers were subject to wear in this area—enough so, that the hammer might begin to drop off, due to inadequate single-action sear engagement—the new hammers don’t seem to wear at all. Smith & Wesson folks tell us their edges remain hard and crisp, and the tighter tolerances guarantee that they will work as intended for a much longer period of time than the old, stamped parts.
Smith & Wesson feels that the MIM parts have also improved the quality of the action, too, as a general rule.
With the old manufacturing method, the notches in the hammers and triggers were made with a fifteen-foot long broach, with the part laying on its side. The broach would leave a bunch of very small tool marks that ran horizontally across the face of the part, leaving a rough surface that looked like a series of ridges and valleys, when viewed through a microscope. These marks increased the drag and friction between the interacting surfaces, and decreased the quality of the action, making it heavier and rougher.
You could polish these out to smooth the action (and many of these old-style parts had to be polished and hand-fitted anyhow, because the manufacturing tolerances varied so much), but the polishing costs additional time and money, and it also shortens the service life of the part. When a case-hardened part (with a thin, hardened “skin”) is polished to fit it to the action, the polishing actually decreases its longevity. The softer materials underneath the surface, which get exposed with the polishing, don’t wear as well, and don’t stand up as long.
The MIM parts eliminate these manufacturing problems. They come out of the molds hard and smooth, with no tool marks on contact surfaces and no need for surface prep. Because their tolerances are tighter, they don’t need to be hand-fitted to make them work. You could stone a MIM part to improve its smoothness (and Smith & Wesson does offer some upgraded actions, via their Performance Center, where the MIM’d parts are given some extra attention to enhance their feel), but they’re already smoother than the old broached and case-hardened parts when they come off the assembly line, and Smith & Wesson believes they deliver better actions than the old parts did, out of the box.4
Fans of the old guns might disagree with that characterization, particularly if they have a smooth example in their collection, that benefitted from some talented hand-fitting, but from the standpoint of the manufacturer, pumping out seven or eight hundred guns a day, the MIM parts do a better job, on the whole, of delivering consistent, quality actions than the old broached parts did.
The new MIM action parts are also engineered to simplify and improve the design.
In the old hammer and trigger assemblies, for example, pins were used to hold all the parts together. The sear, sear spring, and stirrup were all held in place on the hammer by pins, but the new MIM hammer was built in a way that these parts fit into special pockets and are held captive without using pins.
This is important, because these parts were frequently damaged during assembly, in the old process, when the pins were being driven into place. This scrap increased the per-unit cost, and slowed production. Additionally, it’s easy to lose these small pins when doing maintenance on the gun, so the simplified design offers an advantage, there (although armorer friends tell me it can be a little more tricky to get the pin-less assemblies back into the gun, because they lack some of the tools and fixtures that the company has).
Other elements of the gun have improved as well, as a result of using MIM production.
The new-design thumb piece, for example, with its angled contact point and more rounded edges, is a more comfortable and ergonomic part than the old one was, but it would have been cost-prohibitive to build this new part using the old process. With MIM manufacturing, this complex-shape part can be made quite economically, giving the user a better control for less money.
The MIM process has even allowed Smith & Wesson to source a one-piece barrel for the Model 36 that helps to keep costs down, and make the gun more affordable.
Parmatech MIMs the Model 36 barrel for Smith & Wesson, which is restricted to .38 Special +P pressures, only. They only make barrels for the carbon steel frame guns (the stainless and aluminum frame guns use machined stainless barrels, not MIM) because you can’t get a good color match for the stainless and aluminum frames with MIM alloys, but the MIM barrel looks right on the blued Model 36, and saves money.
The Bottom Line
This is just a sample of the enhancements that MIM parts have allowed, but it gives you a flavor for why Smith & Wesson made the leap to this new manufacturing technology.
In the view of Smith & Wesson, the new guns are stronger and better than the old guns, are simpler to make, and more economical to produce. The new MIM parts may not be as attractive as the old case-hardened and blued parts, in the opinions of some customers, but the cosmetics are still good and they’ve allowed Smith & Wesson to continue manufacturing these guns at a price that’s within reach of the consumer.
If Smith & Wesson had to keep building the guns the old way, with all kinds of hand-fitting, they couldn’t sell them for a price that anyone would be willing to pay. A new-production K-Frame revolver would probably cost you upwards of $2,000 if Smith & Wesson was still employing an army of skilled machinists, polishers and fitters to build it. The modern manufacturing methods allow Smith & Wesson to produce a stronger, easier to assemble gun, at a reasonable price point for the consumer.
Despite the earnest attempts to improve the new guns, it’s still difficult to get many long-time Smith & Wesson revolver fans excited about them.
A lot of us have strong emotional attachments to the older guns, which are not only more attractive, but in some cases, smoother in operation, due to the hand-fitting that was required to make them work. They are also reminders of, and links to, a past that we enjoyed very much.
In some cases, the old guns are prized more than the MIM guns because there’s no modern equivalent. If you really loved the old Model 12 Airweight M&P, the .41 Magnum Model 58, the Mountain Guns, or the .45 ACP target guns, then you’re out of luck, as a buyer, today. There’s no MIM equivalent to these guns in the current catalog.
If you’re a gunsmith, you probably think the new MIM guns are more difficult to work on. It’s harder to cut off a MIM hammer spur, for example, because they’re made of harder stuff. If a customer wants you to remove and reinstall one of the new, two-piece barrels, you can’t, because it requires a tool that Smith & Wesson has not made available outside the factory. The new, two-piece barrel design solved a lot of problems for Smith & Wesson from a manufacturing standpoint, and has some definite advantages (which we’ll discuss in an upcoming article), but it sure makes life a lot tougher for those who work on the guns in the aftermarket.
The Elephant in the Room
Then there’s the damned lock, which crept into the guns shortly after the MIM parts did.5
We’re no fan of the lock here at RevolverGuy, and we think it’s done more to harm Smith & Wesson’s sales and reputation than they understand, but that’s a conversation we’ve already had. We won’t harp on it here, but we do think it’s reasonable that at least some of the antipathy towards “the MIM guns” is actually generated by lock hatred. The MIM improvements suffer by association with the lock, receiving collateral damage.
Some of our Smith & Wesson friends have confided that they understand the locks are still controversial, but they encourage us to not throw the baby out with the bathwater. “People can hate the lock, and I understand,” said one, “but if they had any idea of how difficult the journey was to improve these revolvers from the old to the new design, they would feel much better about the new product.”
“We made these (MIM) changes to improve the gun, not to cheapen it,” said another. “We didn’t just make these changes to save money, we honestly felt that they made the gun stronger and better.”
A Fresh Look?
I honestly haven’t spent much time with the MIM guns. I’ve shot a few here and there, but I don’t buy them, because the lock has kept me away from them.
This educational journey about MIM and the new designs has me thinking about my prejudices, though. I’ll never approve of the lock, but perhaps it’s time for me to look beyond that, and appreciate all the other good things these guns have to offer? Maybe I need to focus more on what’s right about these guns, and less on what’s not? Maybe it’s time for me to get some real, firsthand experience with the new MIM guns?
I don’t know, that’s a hard pill to swallow, but I do know that I appreciate the education I received in the course of researching and writing this series, and I hope you’ve learned as much as I have about these guns and the MIM process. I appreciate the hard work of the Smith & Wesson team over the years, and their efforts to make these guns available and affordable, so future generations of shooters can become RevolverGuys, too.
RevolverGuy would like to thank Craig Mariani (the former Team Leader of the Smith & Wesson Revolver Engineering Team) and Norm Spencer (a Smith & Wesson Machinist, Model Maker, and Manufacturing Engineer) for their assistance with this project. The education they provided was critical to our understanding of MIM technology and the manufacturing changes that occurred at Smith & Wesson during their tenure. We would also like to thank the team at ARC Group Worldwide, for their information and assistance. Thank you, gentlemen, for sharing your experience and knowledge with us!
Ruger certainly made a name for itself in the casting business, but that doesn’t mean it’s overlooked other manufacturing technologies. In fact, Ruger is doing a lot of MIM manufacturing themselves, these days, and also contracts out for other MIM parts.
In November 2014, Ruger purchased Megamet Solid Metals Inc., a MIM company based in St. Louis, Missouri, to secure an in-house MIM production capability. Since that time, Ruger has been incorporating MIM parts into many of their favorite revolvers, such as the SP101, the GP100, and the new Wrangler (whose action parts are almost all MIM, which allows Ruger to offer the gun at such a competitive price).
CEO Mike Fifer stated that having an in-house MIM production capability definitely speeds up new product development. Instead of having to wait for extended turnaround times from outside vendors, Ruger can modify and improve parts and molds much faster by keeping them under their roof.
Our own SH Bond, an experienced law enforcement armorer who worked on these guns, says the Baker Mark III design was a definite improvement over the earlier guns, which were based on the 1892 Army and Navy. It substituted a coil spring for the more troublesome leaf spring used in previous Colt designs, and incorporated other enhancements, like a bolt that was powered by a simple mousetrap spring, instead of the Rube Goldberg arrangement that ran off Colt’s V-mainspring. From an armorer’s perspective, it was a stronger, simpler action, and easier to maintain than the traditional Colt revolver action.
Gunsmith Nelson Ford notes, however, that Colt didn’t spring the gun properly, and both the coil mainspring and bolt spring were too weak for the job. He also had several negative experiences with the compressed powdered metal parts, to include a hammer spur that broke off and struck him in the forehead during firing. Alas, the new-style parts just didn’t live up to the promise of Baker’s rugged, new design.
Both Bond and Nelson lament that Colt chose to use a modified V-spring (a “U-spring”) in their new Cobra and Python actions, wishing that they had followed the S&W/Baker model, instead. It may not have satisfied Colt purists, but it would have made for a better, more readily serviceable, gun;
The move towards CNC machining was also part of this industrial revolution at Springfield. We briefly touched on some of the advantages of CNC machining in previous installments, but we haven’t given it the attention that it deserves in this focused series on MIM technology. Perhaps we’ll dive into CNC in the future, but for now, it’s important to understand that the old system of building guns with human-operated machine tools was supplanted by CNC machining and MIM at Smith & Wesson during this era. These were complimentary technologies, which allowed S&W to completely modernize their methods of manufacture, and it would be misleading to ignore half the story by only mentioning MIM;
I’d be remiss if I didn’t note there’s a number of gunsmiths and aficionados that would disagree. There’s some very knowledgeable folks who feel the pre-MIM actions were generally better than the MIM actions, and I’m in no position, given my lack of experience with the MIM guns, to refute it. For now, I’ll simply acknowledge that it’s Smith & Wesson’s position that they’re able to produce a better, stronger action, with less expense and effort, by using MIM action parts, and I’ll leave it for the individual shooter to decide for themself if they agree. If you’ve done a lot of shooting with the MIM guns, please make sure to tell us what you think of them, in the comments, below. How do they compare, in your experience, to the guns made prior to MIM?
The first MIM parts started going into Smith & Wesson’s guns in 1994, with a heavy increase, year over year, from 1995-2010, and the internal lock was added around 2001. While the MIM parts beat the lock by seven years, the new additions happened close enough to each other that a lot of RevolverGuys tend to remember them as a package deal. We were just starting to recognize and digest the MIM changes when the lock was added, and over time we’ve remembered them as one big change. Heck, I guess a span of seven years is close to “the same time” when you’re talking about a design that had already been in production for almost 100 years, at that point.