Smith & Wesson Model 66

Model 66 vs. Model 686: K-Frame or L-Frame for .357 Magnum?

The Model 66 is built on the K-Frame; the Model 686 uses the larger L-Frame. Both are stainless .357 Magnum revolvers with six-round cylinders, but the K-Frame is meaningfully more compact—lighter (36.6 oz vs. 44.9 oz in 4″ configuration) and slimmer through the cylinder. The trade-off is longevity under heavy magnum use: S&W recommends against a steady diet of full-power .357 Magnum in K-Frame revolvers, as the forcing cone and cylinder can show accelerated wear over tens of thousands of magnum rounds. For a shooter who runs mostly .38 Special +P with occasional .357 Magnum for defense or hunting, the Model 66 is ideal. For a shooter who plans to run thousands of magnum rounds per year, the L-Frame 686 is the more durable long-term platform.

What Barrel Lengths Are Available for the Model 66?

The reintroduced Model 66 is offered in 2.75″ and 4.25″ barrel lengths. The 2.75″ barrel is the carry-optimized configuration—it conceals well in an IWB or OWB holster and remains manageable with .357 Magnum, though muzzle blast is substantial with full-power loads. The 4.25″ barrel provides a better sight radius, meaningfully more velocity with .357 Magnum (approximately 75–100 fps over the 2.75″ barrel), and a better balance for range and duty use. Both variants use an adjustable rear sight, which is an advantage over fixed-sight carry revolvers for shooters who want to dial in point of impact with their carry load.

The Model 66’s History in Law Enforcement

The Model 66 was the service revolver of choice for many American law enforcement agencies from its introduction in 1970 through the transition to semi-automatics in the late 1980s and early 1990s. The California Highway Patrol, FBI, and numerous state and local agencies issued the 66 as a standard sidearm. Its stainless construction was a significant practical upgrade over the blued Model 19 it paralleled, as the stainless resisted holster wear and sweat corrosion in daily carry. The Combat Magnum name reflects its original purpose: a compact, duty-capable revolver chambered for the most powerful widely available police cartridge of the era.

Is the Model 66 a Good Concealed Carry Revolver Today?

The Model 66 in 2.75″ configuration is a capable concealed carry revolver for shooters who prefer the manual of arms and reliability profile of a double-action revolver over a semi-automatic. At 36.6 oz unloaded it’s heavier than modern compact semi-autos, which limits all-day carry comfort for some users. Its six-round capacity is the primary tactical limitation. Against those trade-offs: zero manual safeties, absolute feed reliability regardless of grip or ammunition, and the ability to deliver a 125-grain .357 JHP at roughly 1,300 fps from a 2.75″ barrel. For a shooter who carries in a duty-style belt holster or wants a nightstand revolver that doubles as a carry gun, the Model 66 is a compelling choice.

Model 66 vs. Ruger GP100: Which .357 K/L-Frame Wins?

The Ruger GP100 is the most direct competitor to the Model 66 in the stainless .357 Magnum category. The GP100 is built on a larger, heavier frame with a triple-locking cylinder—it’s essentially indestructible under heavy magnum use where the K-Frame Model 66 shows wear over time. The Model 66 is lighter, more compact, and offers a smoother factory trigger and better-fitting grips for most hand sizes. For a shooter who wants the lightest and most compact stainless .357 with excellent ergonomics, the Model 66 wins. For a shooter who will run thousands of full-power magnum rounds and wants the most durable platform, the GP100 is the better long-term investment.

Related Pages

Browse all Smith & Wesson firearms, explore the Model 686 for the L-Frame alternative, or shop our full revolver selection.