By Thomas Kirk, Owner at Premium Grips
Quick answer: Smith & Wesson names its revolver frames by size with letters. The J frame is small, the K frame is medium, the L frame is a heavier medium frame, the N frame is large, and the X frame is the largest. K and L frames share the same grip frame. To find your frame, look up the model number stamped on the frame under the barrel.
Smith & Wesson uses letters to name its revolver frames, and the frame gets bigger as you move down the alphabet. Your frame decides which holsters and grips fit your gun, so it’s the first thing to know before you buy accessories.
We finish and fit replacement grips for S&W J and K frames in North Carolina, and every order starts with the same question: which frame do you have? This guide answers that question for each of the S&W revolver frames, with the models built on each one and the quick check that tells you which frame you own.
What Do the Letters on S&W Revolver Frames Mean?
The letter names the size of the frame, not the caliber. In 1957, Smith & Wesson also gave each revolver a model number. The Chiefs Special became the Model 36, and the Military & Police became the Model 10.
Caliber alone won’t tell you the frame. S&W has chambered .357 Magnum on the J, K, L and N frames. The model number is the reliable guide.
S&W Revolver Frame Size Chart
| Frame | Size | Common calibers | Popular models | Grip frame |
|---|---|---|---|---|
| J | Small | .38 Special, .357 Magnum, .22 LR | 36, 60, 442, 642, 637, 340 PD, 360 | Small |
| K | Medium | .38 Special, .357 Magnum, .22 LR | 10, 13, 15, 17, 19, 64, 66, 617 | Medium |
| L | Medium, heavier | .357 Magnum, .44 Special | 586, 686, 696 | Medium (same as K) |
| N | Large | .44 Magnum, .45 ACP, .41 Magnum, .357 Magnum | 27, 28, 29, 57, 625, 627, 629 | Large |
| X | Extra large | .500 S&W, .460 S&W | S&W 500, 460XVR | Check the grip maker’s fit list |
J Frame: The Small Carry Revolver
The J frame is Smith & Wesson’s small revolver frame and its most popular carry revolver. S&W introduced it in 1950 as a slightly larger version of the I frame from 1894. The first J frame was the Chiefs Special, named at the 1950 International Association of Chiefs of Police conference, according to American Rifleman. It became the Model 36 in 1957.
Most J frames hold five rounds. Popular models include:
- Model 36 and Model 60: the classic steel and stainless snub-noses
- 442 and 642 Airweight: lightweight, with a fully enclosed hammer
- 637 and 638 Airweight: the 637 has an exposed hammer, and the 638 has a shrouded hammer
- Model 38 and Model 49 Bodyguard: older J frames with a shrouded hammer
- 340 PD and 360: lightweight models that fire .357 Magnum
Most J frames today have a round butt. The small grip frame keeps the gun easy to carry, but it gives large hands little to hold. That’s why many owners fit wrap-around grips that cover the backstrap. For the classic Model 36 look, faux ivory is a popular choice. You can see every style in our J-frame revolver grips.
Don’t confuse the two Bodyguards. The older Model 38 and 49 Bodyguard are true J frames. The newer Bodyguard 38 has a polymer frame and doesn’t take standard J-frame grips.
K Frame: The Classic Service Revolver
The K frame is Smith & Wesson’s medium revolver frame. Police carried K frames for most of the 20th century. The Model 10 sold more than 6,000,000 units, making it the best-selling revolver of that century, according to Let’s Go Shooting.
K frames usually hold six rounds. Well-known models include:
- Model 10: the Military & Police in .38 Special
- Model 13 and Model 65: .357 Magnum service revolvers
- Model 15 and Model 19: the Combat Masterpiece and Combat Magnum
- Model 64 and Model 66: stainless versions of the Model 10 and Model 19
- Model 17 and Model 617: .22 LR target revolvers
Many older K frames still wear worn or cracked factory stocks. If yours has a square butt, our K-frame grips for square butt models include classic white pearl, which suits the traditional look of a Model 10.
L Frame: A K Frame With a Bigger Cylinder
The L frame is Smith & Wesson’s heavier medium frame, built to handle a steady diet of .357 Magnum. S&W introduced it in 1980 with the 586. The stainless 686 followed.
The main difference from the K frame is the cylinder. A K-frame cylinder measures about 1.45 inches across, and an L-frame cylinder measures about 1.56 inches. The extra size lets some L frames, like the 686 Plus, hold seven rounds. Many L frames also have a full underlug, which adds weight up front and reduces felt recoil.
The grip frame stays the same. K and L frames share the same grip size and shape, which is why grip makers often list them together as “K/L frame.” Check the butt shape before you buy, because most L frames made in recent years have a round butt.
N Frame: The Large Magnum Frame
The N frame is Smith & Wesson’s large revolver frame, built for powerful cartridges. It carries the .44 Magnum Model 29, the .357 Magnum Model 27 and Model 28, the .41 Magnum Model 57 and the .45 ACP Model 625. Current models include the 627, 629 and TRR8.
N frames have a larger grip frame than K and L frames, so K or L grips won’t fit an N frame.
X Frame: The Largest S&W Revolver
The X frame is the largest revolver frame Smith & Wesson makes. S&W built it for the .500 S&W Magnum and .460 S&W Magnum hunting cartridges. Models include the S&W 500 and the 460XVR.
Some grip makers group the X-frame grip frame with K and L frames, while others list it separately. Always check the maker’s fit list before you order X-frame grips.
Round Butt vs Square Butt: The Detail That Changes Grip Fit
Every S&W frame size comes in two grip-frame shapes:
- Round butt: the bottom rear corner of the grip frame is curved. It carries well and prints less under clothing.
- Square butt: the bottom of the grip frame is flat, with a sharp rear corner. It gives your hand more to hold.
The shape matters as much as the frame letter. Standard grips fit only the butt shape they’re made for. Some makers sell “conversion” grips that give a round-butt frame the fuller feel of a square-butt grip.
History explains why both shapes exist. S&W added square-butt J frames in 1952 because early round-butt Chiefs Specials were hard to control in duty use. Today, many newer K, L and N frames ship with a round butt.
The difference is easy to see side by side. Compare our round butt J-frame rosewood grips with our square butt K-frame rosewood grips. Both use rosewood, but the bottom of each grip follows its frame.
How to Tell What Frame Your S&W Revolver Is
Use these three checks:
- Find the model number. Swing the cylinder out and look at the frame just below the barrel, where the crane (yoke) sits. Most S&W revolvers made since 1957 have the model number stamped there, often with a dash number such as 10-5 or 66-2.
- Match the model number to a frame. Use the lookup list below.
- Check the butt shape. Remove one grip panel and look at the bottom of the grip frame. Curved means round butt. Flat with a sharp corner means square butt.
S&W Model Number to Frame Lookup
- J frame: 36, 37, 38, 40, 42, 49, 60, 63, 317, 340, 342, 351, 360, 442, 637, 638, 640, 642, 649
- K frame: 10, 12, 13, 14, 15, 16, 17, 18, 19, 48, 64, 65, 66, 67, 617
- L frame: 581, 586, 681, 686, 696
- N frame: 20, 21, 22, 24, 25, 26, 27, 28, 29, 57, 58, 625, 627, 629, 657, TRR8
- X frame: S&W 500, 460XVR
If your revolver has no model number, it was likely made before 1957. The Smith & Wesson Historical Foundation can research older revolvers by serial number.
Once you know your frame and butt shape, you can choose grips for Smith & Wesson revolvers with confidence.
S&W Revolver Frames FAQ
What is a J frame revolver?
A J frame is Smith & Wesson’s small revolver frame, introduced in 1950. Most J frames hold five rounds of .38 Special or .357 Magnum. Popular J-frame models include the Model 36, Model 60, 442, 642 and 637.
Is the S&W 686 a K frame or an L frame?
The Smith & Wesson 686 is an L frame. It has a larger cylinder than a K frame but uses the same grip size and shape, so K and L frames share grips when the butt shape matches.
What frame is the Smith & Wesson Model 10?
The Smith & Wesson Model 10 is a K frame. It is a medium-frame, six-shot .38 Special revolver and the best-selling revolver of the 20th century.
Are K-frame and L-frame grips the same?
Yes, when the butt shape matches. Smith & Wesson K and L frames share the same grip frame. Square-butt grips fit square-butt K and L frames, and round-butt grips fit round-butt K and L frames.
What is the largest Smith & Wesson revolver frame?
The X frame is the largest Smith & Wesson revolver frame. S&W built it for the .500 S&W Magnum and .460 S&W Magnum cartridges.
How do I find the model number on my S&W revolver?
Swing the cylinder out and look at the frame just below the barrel, where the crane sits. Smith & Wesson stamps the model number there on most revolvers made since 1957.
Do J-frame grips fit the Bodyguard 38?
No. The newer Smith & Wesson Bodyguard 38 has a polymer frame and doesn’t take standard J-frame grips. The older Model 38 and Model 49 Bodyguard are J frames and do take J-frame grips.
Know Your Frame Before You Buy
The letter on your Smith & Wesson revolver frame tells you its size, and the butt shape tells you its grip fit. Check both before you order holsters or grips.
Not sure about your frame? Contact us with your model number, and we’ll tell you which of our grips fit. Every set from Premium Grips comes with a 30-day guarantee.
About the author: Thomas Kirk is owner at Premium Grips. Our team finishes and fits replacement grips in North Carolina for Smith & Wesson, Colt, 1911, Heritage and Ruger owners.
