I have a 686 PC 2.5 inch. I called Smith and they said my barrel and frame are forged. Is the cylinder forged or machined? Thx.

I can't say, but even forged parts require machining.

Darn, not one of thoes laying so you can see where the side plate will be cut.

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John

This is a picture of a board that hung on the wall a S&W in Springfield. Don't know if it's still there, since the gun it depicts is pretty old. Shows many of the major components as they would of progressed at each major step in the manufacturing process. I thought it was interesting, and due to it's age it's not super relevant to the OP's topic, but I've been waiting a long time for a thread to post it in...........

Attached Images

S&W Manufacturing Steps, FBI Academy Armory x2.jpg (266.0 KB, 798 views)

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~ S&W aficionado in training ~

I just have to ask. What did you think the alternative to a forging might be and even more importantly, why did you ask?

Bruce

The alternative is machining out of a non forged stock. I ask because people say forged is superior. So far, no one has answered my question.

We also have neglected "MIM", the most evil concept ever. Call it plastic metal if you must.

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Dick Burg

What is the exact process on the mim parts?

Casted 4140 steel, forged, machined, then hardened? Drop in part?

I doubt there is any other method to produced a strong enough metal part to become a revolver cylinder than forging the appropriate material into round bar stock, then cutting to appropriate length, machining processes to final form and heat treating and finishing as appropriate. This is a good basic description:

How revolver is made - material, making, used, parts, components, procedure, industry, machine

PS I do not work in this field so I may be wrong. By the way, can you call the factory back and ask them about how cylinders are made? They gave you a good answer on the barrel and frame...

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Alan
SWCA LM 2023, SWHF 220

Turn the picture over

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Some collect art; I shoot it!

At least before MIM the forged parts in a S&W revolver were barrel, yoke, frame, trigger, hammer and, I believe, the cylinder stop and bolt. The cylinders are made from round bar stock, and probably always have been. The lockwork recess in the frame is part of the forging process.

It isn't so much that forging is technologically superior to machining from solid stock as it is a far more cost effective method of fabrication. Even though all surfaces must still be machined, there is far less metal to remove from a forging that can be produced very close to finished dimensions.

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Gunsmithing since 1961

Well, at least someone knows . But is round bar stock forged into that shape?

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Alan
SWCA LM 2023, SWHF 220

A forging will have superior mechanical properties to a casting, when the intended purpose is building a strong firearm.

That doesn't mean that forgings are the only way to have high strength steel parts.

Quality bar stock parts (ASTM A331 4140 chromium/molybdenum steel for example) that are properly heat treated can exceed forged steel mechanical properties.

Producing a high quality steel revolver is an expensive process. Drop forging frames and hammer forging barrels is cost effective due to the shapes. The frame is a flat part that is relatively simple to forge. The barrel can be hammer forged around a mandrel.

The cylinder is a different matter it has 5, 6, 7, or 8 chambers that are off center to the axis, forging this part is not an option. Starting with very good ASTM A331 steel and post heat treating will produce a part that is superior to a forging.

Think about it, when a .44 Magnum cartridge is ignited, what part takes the highest pressure load? The cylinder, and it isn't forged.

Right!

That's exactly true-NOT.

Bruce

Not a metallurgist here but with past experience with MIM parts.

My company began using MIM parts many years ago, and we got the same trash talk from some customers as we hear about S&W parts today. The proof was in the pudding when they realized that the parts not only did the job but had advantages in many ways. Our engineers had tested the parts seven ways from Sunday before the change was made and were convinced that the change was worthwhile. It proved to be the case after much field experience.

If MIM does not suit your fancy, just buy old models while the rest of us realize the advantages of new technology. I love the old blued guns, but the newer stainless ones are more user friendly. Some are still trying to look back at the blued guns as superior but I much prefer the stainless in wet conditions. Go with whatever floats your boat.

Without such advents such as MIM parts you would be complaining that you couldn't afford a revolver made as some folks see it, old school. Life and technology change and your either your "On the Bus or Off the Bus", Ken Kesey. Would you stop buying late model cars if they weren't built in the same fashion as your "56" Chevy. I doubt it.

This MIM parts thing has actually taken on a life of it's own and a lot of folks have almost an irrational fear of a MIM part failing at the wrong time.

Very high quality MIM parts can be produced to extremely close tolerance and immensely intricate shapes with a wide variety of carbon and stainless steel alloys and a wide range of heat treatment specs. As this process evolves and gets even more refined, it's use in firearms applications will expand just as it has with investment casting. These same investment casting were said to be vastly inferior to forgings when they were originally used-something that has proven to be patently false with the passage of time.

My personal gripe with MIM parts isn't their utility but their aesthetic qualities. Smith and Wesson MIM hammers and triggers look like hell as compared to their CCH forged counterparts. Also, MIM parts used in conjunction with extremely close tolerance CNC machining has given some manufacturers, including Smith & Wesson, the notion that almost all hand fitting and most close manual inspection and QC can be eliminated. That has not proven to be the case in the eyes of their customers however. Continuing issues with canted revolver barrels, poorly fitted thumb safeties and poorly staked plunger tubes on 1911's continue to vex their product. I can see no good reason for this except that possibly their bottom line mandates a policy of "let service clean up after production". It's damaging their consumer satisfaction and perception.

Such is life today.

For the most part, people are irrationally fearful of all MIM parts and are just running scared. Although MIM parts in firearms have been around since at least 1983, the main reason for this fallout can be traced to a single 1911 manufacturer and that goes for the external extractor as used on 1911's also.

Bruce

If the cylinder is cut from bar stock, that is essentially a forged part then. The bar would have started life as a hot slug that gets pounded, rolled and drawn out to its final form. Stock normally comes in three options, cast, hot rolled and cold rolled. The cold rolled being the best.

Let's be accurate about this. First, initially all steel is cast. The molten steel from the furnace is poured into a mould, and when it "freezes" (simply becomes solid from cooling) is processed into dimensional stock by rolling. Alloy steels are hot rolled due to their relative strength requiring this. Typically cold rolled steels are simple Carbon steels which are often not heat-treatable, so-called "mild steel". Bar stock strictly is not forged, but rather rolled to shape, regardless of diameter. While rolling works the metal in very similar fashion to forging it is not the same process at all.

Stock for forging can be either cast or cut from rolled stock, usually referred to as a "slug". This slug, cut to the required dimension to fill the forging die when "struck" is then heated in a furnace and finished to required shape in the forging die, and excess then removed in a separate trimming operation to remove excess material. Subsequent heat-treatment of the forging can be done either after forging and before machining, or after machining operations depending on the required material properties.

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Gunsmithing since 1961

Bar stock made on a bar mill is wrought, it isn't forged. Wrought and forged parts are not at all similar in structure.

The most basic steel forms are: cast, wrought (which would be hot or cold rolled) and forged. Of course there are options withing the basic groups, such as vacuum cast, sand cast, permanent mold casting, etc. And of course other forms , sintered metal, metal injection molding, additive manufacturing (3D printing)

In any case bar stock is typically not forged material. You can buy forged bars, but if extensive machining is to be performed on the final part, forged stock offers little to no advantage.

Selecting the correct steel for a given application is critical. It is far more complicated than choosing "mild steel or chrome moly" ASTM classifications allow for precision engineered alloys and properties.

Machining parts from quality steels of the correct specification then heat treating the parts will produce components that meet the mechanical properties as required. It's a matter of understanding how to select the correct spec steel, use the time-temperature transformation chart and having precise control of the process.

It seems to be common knowledge that modern steels are superior because of better heat treatment. Also, the perception is that steels are better because we are smarter than steel makers 50, 60 or 80 years ago. That isn't really the case. The biggest difference is more accurate, more precise heat treat furnace controls in use today.

Cylinders are probably for forged round stock that has been normalized and annealed. The stock is then hardened and tempered before or after it is partially machined. Finish machining would occur after harden and temper as that process causes a small degree of dimensional change. Forging stock can be and advantage in breaking up and evenly distributing any small imperfections that can occur in casting a billet. But, billets and castings of high quality steels have also improved drastically. Now high end steels are cast in induction furnaces in an inert atmosphere for better initial billets.

You want real high end you can get CMP steels where the steel is melted and alloyed in an inert atmosphere induction oven and then basically sprayed in an inert atmosphere. Forming tiny beads of steel that are then super heated just below the melting point and forge welded into a solid billet that will be completely uniform in alloy content and free from any stratification or small inclusions that can occur in a poured billet. Get out your wallet. A piece big enough for me to make a medium sized hunting knife cost me about $40.

With the advent of Kanthol wire which can take temps up to around 2500f electric furnace have replace gas furnaces for critical HT, for one thing better atmospheric control and even inert atmospheres are possible. With the advent of electronics ovens are controlled with PIDs and solid state relays (SSRs). My oven has a programmable PID that can change temps at a given rate and hold temperatures to within+-1 degree for 32 steps. Even the oils used to quench are now engineered to control the rapid cooling rates.

Plus there is induction heating where parts are subject to high energy electric fields which cause them to heat up.

Heat treating has gone a long ways and so has the testing of the results. Pieces of steel can be polished and magnified to study the resulting grain structures. Heat treating is all about the controlled changing of grain structure and type of structure.