Awesome Airweights: Overview of 3 Smith & Wesson Lightweight J-Frames

Smith & Wesson revolvers are iconic and nearly timeless firearms that remain the fabled manufacturer’s flagship product. Their excellence in manufacture and highly innovative designs has set and continue to set very high benchmarks for wheelgun performance. There is no doubting that S&W makes effective and reliable guns for self-defense.

Without question some of the most numerous, enduring and popular of their offerings rests in their compact, lightweight J-frame revolver lineup, commonly referred to as the Airweight series, or S&W airweights.

Descended decades ago from their initial compact revolver offerings, the Airweight and Airlite series offerings today are engineering marvels combining the best of modern manufacturing techniques with classic design and advanced materials.

These small powerhouses are everything a compact revolver should be, and represent some of the very best guns in their class. Today, we will examine three of the very best among them, the Model 637, Model 642 and Model 340PD and discuss their suitability as defensive handguns.

Genesis of the Airweights

Smith & Wesson’s Airweights are some of the best known and highest quality revolvers on the market in the compact or “snubbie” revolver category. These little wheelguns have much in common between each other and all can trace their lineage to a few common ancestor J-frames in the company’s historic product line.

Before we go too far down that rabbit hole, the J-frame moniker may need some explanation for those newer to the gun scene. Smith & Wesson revolvers can be broadly grouped into families based on the dimensions of their frames: in this instance, J-frame denotes a small frame.

Others abound, with medium frame guns being classed as K-frames, and slightly larger and stronger medium frames being L-frames. Climbing the size and power ladder you’ll arrive at the prodigious N-frame, made famous (or infamous by the mighty .44 Magnum Model 29.

Larger still are the colossal X-frames, with a few models chambering the devastating .500 and .460 Magnums.

A fun bit of S&W trivia is that these tags all started as nothing more than internal product codes for use by the company. The guns were named by year or by model back then, and were advertised accordingly. Smith & Wesson did not tout their guns as a “J-frame” or “N-frame”.

But as is so often the case, factory jargon made its way into the “wild” and soon enthusiasts and fans started referring to Smith & Wesson revolvers by class using the same designations. Today, S&W uses the same codes publicly and in advertising since most shooters have become familiar with what they mean.

The J-frame family is itself several decades old, first appearing in 1950 with the introduction of the classic Model 36, or Chief’s Special, and the progenitor of all of the J-frames we enjoy today. The J-frames were not, though, the first compact S&W revolvers.

Far from it, as the now extinct (well, out of production) I-frames preceded them by many years. At any rate, the Chief’s Special was everything we would recognize as a modern Smith & Wesson compact: 5 shots of .38 Special issuing from a very short barrel along with the familiar (and maligned) fixed sights common to the breed.

The Model 36 was the basis for several equally familiar variants still considered iconic in the J-frame family. Among this distinguished family are included the Bodyguard series and the Centennial series.

While mechanically nearly identical, the principal differenced among them are the configuration of the hammer, specifically whether or not the shooter can interact with it directly.

The Chief’s Special series is most recognizable as a basic DA/SA revolver, possessing as it does an exposed hammer that may be manually cocked to put the gun in single-action mode.

The Centennial series features a completely internal hammer and is in effect a double-action only gun; there is no way to cock it to get that nice, crisp trigger pull.

The Bodyguard series guns split the difference, with an external hammer shrouded so only the spur is exposed, reducing the possibility of a snag while still allowing single-action fire.

Among these three “first families” of snubbies there are and have been many, many variations. Things like finish, caliber, frame material, finish and more all offered in a sometimes bewildering array of variations for the discerning purchaser.

Models 637, 642 and 340PD

Our three subjects today are the 637, an aluminum alloy-framed .38 Special with an exposed hammer, in essence a lightweight Chief’s Special; the 642, an aluminum alloy-framed .38 like the 637, but with an internal hammer, a lightweight Centennial; and the 340PD, a flyweight Centennial, made possible by an incredibly light and strong Scandium alloy frame, a titanium cylinder and chambering the potent .357 Magnum, though it may fire .38’s also.

All of these nice revolvers are instantly recognizable as S&W’s. The arrangement of the cylinder, cylinder release, crane, ejector rod and fire control are all typical of what we have come to expect of Big Blue.

All feature good triggers (as far as J-frames go) with a little bit of noticeable stacking and mild but prominent wall immediately prior to the crisp, sure release. The 637’s single action trigger is excellent, weighing a hair over 3 pounds with no discernible take-up.

The cylinder releases all move smoothly forward allowing the cylinder to swing out of battery to the left, pivoting smoothly on excellently fitted cranes.

The short, abbreviated ejector rods will not clear empty cases or live rounds completely from the cylinder, necessitating the guns be tipped upward and the rod stroked briskly to ensure ejection. This problem is exacerbated slightly with longer .357 Magnum cases in the Model 340PD.

The 637 and 642 both feature attractive satin silver bead-blast finishes while the 340PD comes in a midnight black frame finish offset by a striking, dove gray titanium cylinder. Capacity for all guns is 5 shots for the .38s or the .357s.

Note that the longer .357 Magnums will not fit the shorter chambers of the 637 and 642, a baked-in feature to prevent inevitable disaster that always follows an accidental firing of a drastically powerful round in a gun that was not designed to handle it.

The sights on the 637 and 642 are old-fashioned, machined-in sights, a serrated, tall front ramp and a miniscule rear notch in the top of the frame for a rear. Not the best for fast, precision work, but useable with a little practice and made better with some high visibility sight paint.

Things are better for the 340PD, as it has nice, enclosed green fiber optic front sight, though still mated with the minimalist notch of the other two.

Grip options are all textured rubber as standard, but any round-butt J-frame grips will work. Woods, laminates and synthetic materials of all kinds are available in a huge variety of shapes and textures to fit any hand.


Loading and firing of all three models is totally identical. Depressing the cylinder forward will allow the cylinder to be swung out of the frame 90° to the left for loading and unloading.

If any loaded cartridges or empty cases are in the chambers the muzzle should be tipped up and the ejector rod should be depressed briskly to kick all present out of the gun.

Loading is easily accomplished using single rounds or with speedloaders. The stock grips are relieved for speedloader use but one must test their chosen brand as clearances will nevertheless be very, very close. Once the chambers are loaded the cylinder is swung back into the frame until it locks.

At such time, the gun is loaded and can be fired by pulling the trigger. In the case of the 637, the hammer may be thumbed to the rear for a single action shot. As with all such S&W guns decocking, if required, is strictly a manually accomplished procedure. Proceed with caution.

All three guns feature the often derided keyed internal locking system.

What Can the Snubbie Do For You?

Snubbie revolvers offer an ideal combination of concealability, potent chambering and reliability that is rarely duplicated in semi-autos of the same size class. If you need a gun that will easily carry on an ankle, in an external pocket or even just on your hip, a compact revolver might be just the ticket.

.38 Special is entirely adequate for self-defense, and the .357 Magnum is an extremely effective round as far as handguns go, so our caliber consideration is certainly accommodated. S&W builds very high quality guns and these are no exception, their revolvers, in any category, being among the most robust and reliable available.

Yes, some semis have far greater capacity and may even be smaller, but few come close to the combination of reliability and ample caliber that is a snubbie’s stock and trade while maintaining good shooting and handling characteristics.

Selecting one of these models will be largely determined by preference and also your experience and expertise with handguns. Bottom Line Up Front: a snubbie is an expert’s, not a novice’s, gun. DA triggers take time and practice to master.

Five rounds do not leave much room for error. Slow reloads further hamper that limited capacity. All of these guns have stout recoil, and one (the 340PD) chambering .357’s is positively blistering. Semi’s help ameliorate all of those concerns by design.

All that being said, while semi-autos in general are more robust and reliable than revolvers it is a rare subcompact semi that is as reliable as a compact revolver, chief among its perks being that it cannot be limp-wristed or otherwise shooter-induced to malfunction barring a short stroke on the trigger. Very small semi-autos are notoriously fickle about such things.

If you are certain you want a snubbie for the convenience and reliability factor, read on for my take on each of them.

Gte893m [CC BY-SA 3.0], via Wikimedia Commons

Model 642 – Best All Around

The 642’s light weight married to a modest .38 Special load makes for brisk but manageable and largely tolerable handling. The internal hammer totally eliminates the chance of snagging a hammer spur when drawing, a major SNAFU when drawing from a pocket in particular.

The opportunities to make use of single action fire in defensive shooting will be few and far between, so losing that capability totally is not a big deal.

If you are a seasoned pistol shooter and want to check the most important boxes on defensive snubbie, the 642 is a winner.

Model 637 – Best for Traditionalists

The 637 is essentially the same gun as the 642, only it has an exposed hammer that is capable of being manually cocked for single action fire. While a boon for target shooting and hunting, thumb-cocking will not be possible in most time-sensitive attacks, which is to say all of them.

Furthermore, the exposed hammer spur is prone to snagging on things when drawing and the trigger on a cocked revolver, especially Smith & Wesson’s, are extraordinarily light, and present a significant safety hazard. Don’t do it like they do in the movies.

Even so, there are some people who are just not happy without that exposed hammer and the option to thumb cock if they need to. For them, the 637 is still a fine choice, warts and all.

Model 340PD – Best for Experts

The 340PD Airlite is a gun for experts or masochists and no one else: while it is so light it feels like it may float away on a stiff breeze (thanks to an exotic scandium alloy frame and titanium cylinder) and that makes it a joy to carry, you will pay the piper when it comes time to pull the trigger.

Recoil with this gun firing full-power .38’s is stout, and painful with any .357 Magnum. If you have not mastered your fundamentals this gun will be nearly uncontrollable for follow-up shots. Even if you have, pounding recoil makes practice a bear, and slows down the accurate placement of fire.

There are other quirks, too. This gun is so light you absolutely must test fire the gun using your chosen ammunition: the recoil impulse is so sharp that bullets may be pulled forward out of their cases and preventing the cylinder from rotating.

This ties up the gun hard and is a Very Bad Thing™ to have happen when your life is at stake. S&W has mandated no less than 120gr. bullets be used and even then you must test them for certainty.

Consider this the hotrod of the family: quirky, temperamental, but capable of performance the others are not.

Should YOU Get a Snubbie?

Snubbies are polarizing sidearms. On the one hand they are reliable, potent and a joy to carry as I mentioned above. They are certainly simple to use. All of the handguns featured above are very high quality and come from a maker with a pedigree of making high-quality guns. On the surface there is nothing to disqualify them.

All of that is true but the 637, 642 and 340PD have shortcomings that are inherent to small revolvers as a class, namely very limited ammunition capacity, slow and cumbersome reloading no matter how it is accomplished, tough to manage triggers and generally poor sights compared to more modern handguns of all stripes.

Fans and staunch proponents will waive these concerns: “If I need more than five I deserve to die!” “You’ll be shooting so close you won’t need to aim!” and “It’s an across the table gun, the trigger don’t matter!” Such bunk is just that and a disservice to potential buyers.

Yes, the average defensive shooting will be concluded with just a couple of rounds fired, but not all of them are. Count on the fact that you may miss, your assailant will need more than one shot to be stopped or the fact that he likely has friends with him and suddenly five shots before a challenging (in ideal circumstances) reload is not very comforting.

The sights cannot be excused either. Sighted, well-aimed shots are what win fights. Not point-shooting or wishing for the best. Poor sights are harder to pickup, harder to align with certainty and harder to use quickly compared to nicer sights. The front sight on the 340PD is a boon, but is still marred by a shallow, small rear notch. The 637 and 642 sights are “meh” at best, and changing them beyond a stripe of high-vis paint is a gunsmith operation.

And yes, your fight will likely occur at close range, but a tricky trigger does you no favors when you consider that even an inch of muzzle deviation can result in a clean miss at short range.

A trigger you are more likely to shank is more likely to produce such an outcome. Can this be overcome by training? Of course, but these are not handguns that make things a cinch for you.

Combine the mediocre sights, challenging triggers and brisk to severe recoil and you have guns that are best for dedicated shooters who will pay the toll in blood and time to extract the fruits of their labors. If you are a novice gunhand or just lazy avoid these entirely for your own sake.


In summary, all of these small revolvers are viable defensive handguns that excel in a specific role. Each of them requires considerable practice to shoot to a high level and the 340PD in particular demands a heavy price from its shooter.

If you have the ability and are committed to practicing regularly with them, these lightweight wheelguns can be a great option for concealed or backup work.

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3 thoughts on “Awesome Airweights: Overview of 3 Smith & Wesson Lightweight J-Frames”

  1. I several revolvers, 2 S&W (Governor .45LC/.45ACP/.410GA & Model 19 .357 MAG), 2 Ruger (GP 100 & Security-6 .357 MAG) and Taurus Judge Public Defender. I would only consider the Judge as a “compact” revolver. I lost a Ruger Security-6 due to theft a few years ago. Although that gun had a 2.5″ barrel, it handled the .357 MAG loads very well. It was heavy, so recoil was not an issue. I’d love to get a 340PD, but they are very expensive. I’ve been using the Public Defender as a concealable “back-up” weapon. I admit, recoil is stout with the .410 GA rounds. I would not consider it “painful” or “unmanageable”, though.

  2. I have several wheel guns, most in .22, sure a mouse gun, maybe a rat gun. I tried the Scandium frame and regular steel frame. Both, almost broke my wrist. However, having one hand I expected a recoil. At 70, and having arthritic hands, at least a three inch barrel will absorb the recoil better.
    Both were good guns, they are NOT for those with arthritic hands or slight in stature.

  3. Another great article. I love S&W, but I ended up with a Taurus snubbie with the brushed nickle finish instead. It has a titanium frame and wheel, which I feel is much more visible against a pair of blue jeans in a dark parking lot from 25 feet. To be honest, I chiefly chose this model and make because it has a shrouded hammer so I had the SA/DA option. As you so correctly stated, .357 is a masochistic exercise, while .38 is stout but much more pleasant to shoot. This pistol is my EDC, in any and all locations, so concielability was a chief concern. A snubbie is the ultimate conceal carry in a front pocket behind a folded piece of mail. Being caught empty handed very nearly cost me my life once, I learned my lesson and appreciate my second chance fully. My snubbie is a constant companion.


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