A Brief overwief of the history and the present of the S&W "N" (large) frame revolvers
The N-frame revolvers are the biggest double action ones, that are manufactured by Smith & Wesson conpany. The history of the N-frames began in 1908, with the introduction of the New Century Hand Ejector revolver, chambered for then-new .44 S&W Special cartridge. The gun, also known as a "Triple Lock" model, featured additional cylinder lock at the cylinder crane, plus two standart locks at the front and rear ends of the cylinder axis/ejector rod. Another feature was the enclosed ejector rod (underbarrel lug). The frame was bigger and heavier than the K-frame Hand Ejector, allowing to use larger caliber ammunition. The trigger action was similar to .38 caliber Hand Ejectors, as well as the sights.
In the 1915 the S&W got rid off the Triple Lock feature, as a time-consuming and cost-adding. The underbarrel lug also was removed. After the beginning of the World War One, folowing the demand of the US Army in the sidearms, the S&W rechambered its N-framed second model for US GI .45ACP cartridge. As the .45ACP was rimmles round, the gun should be loaded with ammunition in half-moon clips for proper case extraction. each clip can hold 3 rounds and also speed up loading. These guns were issued to US troops as S&W Model of 1917 revolvers, along with the Colts (issued under the same designation of M1917).
In the mid-1920s came the third model of the N-frame, that brought back the underbarrel lug. In the 1929 S&W developed new round, .38 High Velocity (.38HV) - a heated-up version of the .38 S&W Special. Since this round was unsafe to fire in the K-framed M&P revolvers, S&W team rebarreled the N-framed revolver for .38-caliber (actually, .355in), and installed a heat-treated cylinder that could hold 6 rounds of either .38HV or .38Spl rounds. The gun was named 38/44 Heavy Duty (Model 20, since 1956). Similar model with ajustable sights was called the .38/44 Outdoorsman (model 22).
The development of the .38HV cartridge (also known as .38/44) and the Heavy Duty revolver led to the invention of the .357 magnum round - a lenghtened version of the .38HV. The only reason for case lenghtening was to avoid chambering hot amunition into guns that were not designed for such ammo. The first revolvers in the .357magnum by S&W were similar to .38/44's, except for the longer cylinder. Since the 1956, this model received the designation Model 27. During 1980's, the Model 27 was replaced by its stainless steel version, model 627. Currently, model 627 is offered in limited numbers from S&W Performance Shop, with standart 6 round cylinders or with "high capacity" 8 rounds unfluted cylinders. A "budget" version of the Model 27, model 28, originally known as "Highway Patrolman", was very popular police sidearm in the USA during the 1950's-60's. The Model 28 difered form the Model 27 mostly by having less "luxury" finish, while maitaining almost the same strenght, reliability and accuracy.
During 1920's-50's S&W also developed some target models in .44spl, that differed from standart ones by having ajustable sights (post-1956 guns also known as Model 24's), and in 1950s S&W introduced target revolvers chamvered in .45ACP, using same half-moon clips as M1917's. These models are known as Model 25's, and currently are in limited production by S&W Performance Shop.
In the mid-1950s, folllowing the demand from the hunters and shooters in the more powerful cartridge/gun, S&W and Remington developed the pair that for couple of decades became the most powerful handgun/cartridge combo in the world. namely, these were .44 remington Magnum cartridge and S&W .44 Magnum revolver, later renamed in the model 29. Back in the 1980's the model 29 was replaced by its stainless steel version, the Model 629, that is still in production. Most common versions are model 629 standart with old-style, short underbarrel lugs, or 629 "Classic" models with full-lenght, heavier underbarrel lugs. All variant of the model 629 featured ajustable sights.
In the 1967, the S&W and Remington decided to introducea gun/ammo combination that will fill the gap between .357mag and .44mag guns. The result was the .41 remington magnum cartridge and the S&W Models 57 and 58 revolvers. Model 58 featured standart N-frame with fixed sights, and was intended for police and state troopers use. Model 57 featured fixed sights. However, these guns did not catch the market well, mostly because these were still too powerful (with too big recoil and muzzle blast) for many law officers. The stainless steel of the model 57, the Model 657, is still being manufactured by S&W.
With the introduction of the new, powerful pistol cartridge, 10 mm auto, S&W began to manufacture the Model 610 - 6-round revolver, that should be loaded with ammunition in full- or half-moon clips. As with other 6xx serties revolvers, Model 610 featured stainless steel construction and ajustable sights.