The S&W K-frame and the .38 Special Cartridge

Glen

Moderator
Staff member
The S&W K-frame and the .38 Special Cartridge

Most handgunners realize that there was a paradigm shift that happened in 1873 with the introduction of the Colt Single Action Army and the .45 Colt cartridge. Perhaps not as many realize that there was an equally important jump in 1899. What happened in 1899? S&W introduced the K-frame and the .38 Special cartridge.

vintage K38s b.jpg
Model of 1899, 1st Model Military & Police (top), and Model of 1905 M&P Target (bottom).

Yes, there were double action revolvers before the 1st Model M&P (e.g. the Colt Lightning, the S&W 1896, etc.), but they were weak, tended to break easily, and were unreliable. With the K-frame, S&W gave the American shooter an affordable revolver that was readily available, reliable, and would serve long into the future. With the .38 Special, with a 158 grain bullet at about 850 fps, S&W gave the shooting world one of the most useful handgun cartridges of all time. The 1st Model M&P was truly a landmark.

Originally the M&P was built on a round-butt (RB) gripframe only. The square-butt (SB) gripframe was introduced in 1905. These guns were available with either fixed sights or adjustable sight Target Models. In my experience with the M&P, these fixed sight guns are almost always well-regulated for 158 grain .38 Special load at 850 fps. In either form, it went on to become the definitive law enforcement sidearm for most of the 20th century.

In 1902 and again in 1905, there were some improvements made to the internal lockwork.

As fine a round as the .38 Special is, the 158 lead round nose ammo was noted for not being as effective as needed at times, and this led to development of the flat-nose semi-wadcutter (SWC) load, and eventually the SWC-HP load (aka “FBI Load”). These both represented significant improvements in the performance of the ammunition.

Side note – S&W brought out the .38 Special in the N-frame (Heavy Duty and Outdoorsman in 1930 and 1931, respectively), leading to experimentation with high pressure loads (+P and +P+) loads, eventually leading to the introduction of the .357 Magnum in 1935. That is a different story…

Second side note – None of the revolvers made before 1916 had heat treated cylinders or barrels, meaning these guns were basically made of mild steel. These guns should not be shot with +P loads or jacketed bullets. Heat treated cylinders began at about SN 316648 (~1916), heat treated barrels came a little later. The early guns should be shot with standard pressure lead bullet loads only.

The K-frames and the .38 Special played a role in WWII in the form for sidearms for some MPs/SPs, and later in the form of Victory Models.

To the best of my knowledge, all of the K-framed .38s made up to this point were tapered “pencil barreled” revolvers.

After the War, S&W made a few changes to the K-frame – they introduced the new “short action”, and they introduced some new K-38s with heavier barrels and full length ribs – the K-38 Target Masterpiece (6” barrel, Patridge front sight) and the K-38 Combat Masterpiece (4” barrel, Baughman front sight).

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Postwar 5-screw K-38s: 6" Target Masterpiece (top), and 4" Combat Masterpiece (bottom).

In the early 1950s, S&W even introduced some lightweight aluminum framed K-38s in the M&P Airweight, and Aircrewman revolvers. These models were short-lived, and not very many were made.

The 5th screw was dropped in late 1955, so guns made after this point are referred to as 4-screw guns. S&W started replaced their model names with model numbers in late 1957 (e.g. the M&P became the Model 10, the K-38 Target Masterpiece became the Model 14, and the Combat Masterpiece became the Model 15). 4-screw guns were made up until 1962. As a result, there are 4-screw S&Ws that have no model number stamped inside the frame, and there are 4-screw guns that DO have the model number stamped inside the frame, all depending on when they were made.

A couple of noteworthy variations of the K-38 were introduced in 1959. Most importantly, S&W came out with a 4” heavy barrel (HB) version of the Model 10 in 1959. This combination gave the shooter the balance of a 6” revolver with a more compact 4” gun (i.e. more easily carried in a holster while seated in an automobile, not to mention being more concealable). This combination was very popular with law enforcement, as well as shooters interested in personal protection/home defense. Also in 1959, S&W Introduced Model 14s with an 8 3/8” barrel. This longer sight radius made this very accurate sixgun easy to shoot well, making it well-suited for bullseye competition and small game/varmint hunting.

K-38s introduced in 1959 50 percent.jpg
The 4” HB Model 10 and 8 3/8” Model 14 were introduced in 1959 (Hogue fingergroove grips are aftermarket additions).

The 4” HB Model 10 is arguably the perfect plinking gun, truck gun, and nightstand gun. In fact, I have one lying right next to my laptop as I type this. Later they would make 2 ½” and 3” HB Model 10s as well. The 3” HB Model 10 is one of my favorite carry guns.

S&W 3 inch M10 HB and SR holster.jpg
The S&W 3 inch HB Model 10, with the excellent Simply Rugged pancake holster, and Keith HP ammo.

S&W dropped the 4th screw in 1962, guns made thereafter are referred to as 3-screw guns (how clever!).

A big change came to the K-38 in 1970 when S&W started making them out of stainless steel. First was the Model 64 (fixed sight, M&P Stainless, in 1970) and 2 years later came the Model 67 (adjustable sight, Combat Masterpiece Stainless, in 1972).

4 inch HB Model 64 DAO.jpg
Stainless steel K-frame -- 4" HB Model 64 (in this case, a DAO gun).

In 1991 S&W introduced a full-lugged version of the Model 14. A full lug make a gun more muzzle heavy, and tends to slow down sight wobble, making these guns popular in various forms of competition (especially bowling pin and falling plate competitions).

Masters Gun with new grips.jpg
S&W started making full-lugged Model 14s in 1991 (pictured is a 60s vintage gun with a 90s vintage barrel mounted, affectionately known as "The Master's Gun").

My favorites? I like them all, but my favorites are the 5-screw guns from the first half of the 1950s, the 4” HB Model 10s, and the Master’s Gun (for sentimental reasons). I prefer 3” revolvers for concealed carry and the 3” HB Model 10 is an accurate and reliable old friend.

Favorite loads? Superb .38 Special ammunition can be assembled using virtually any fast burning pistol powder. That being said, I do have a few favorites – with 158-160 cast SWCs (like the H&G #51 or the SAECO #382), I like 3.6 grains of Bullseye, or 4.0 grains of PB, or 5.0 grains of Unique, all for ~800-850 fps). For a +P load, I have gotten excellent results using the Keith HP (Lyman/Ideal 358439) over 8.5 grains of HS-7 for about 1050 fps from a 6” revolver (about 19,000 CUP). The Keith HP expands very nicely at these speeds when cast to a BHN of about 9. Sadly, HS-7 has been discontinued, but similar loads can be worked up with powders of similar burning rates (HS-6 and AA #7 have shown promise in early experiments).

The K-frame .38 Special has been in continuous production for over 120 years, with untold numbers of guns made. Why? Because it’s a very useful gun – it’s easy to learn on, it’s easier that most handguns to master, it’s good for law enforcement, it’s good for personal protection, for home defense, for concealed carry, it’s good for plinking, it’s good for competition, it’s a good first gun, it’s a good last ditch gun. It’s just flat a good gun. That’s why.
 
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Glen

Moderator
Staff member
It has been pointed out that the Aluminum framed Aiweight M&P was made up until 1986 as the Model 12. Total production numbers for the Model 12 are not given in the Standard Catalog of Smith & Wesson, but they are not very common.