the Model 18 was designed as a training weapon for law enforcement officials and others who primarily carried Model 10's, 15's and 19's-.38 Special and .357 caliber revolvers. The Model 18 (like the Model 17) operates and handles in a similar fashion to these law enforcement models of the day; and closely shares the size, weight, grips, internal mechanism, and operation of several popular "K" framed revolvers like the Model 10 (.38 Cal.), Model 13 (.38 & .357 Cal.), Model 14 (.38 Cal.), Model 15 (.38 Cal.) and Model 19 (.38 & .357 Cal.) The only significant difference was the Model 18's .22 caliber. With the introduction of the Model 17 with full under lug barrels, Smith & Wesson also began production of the .22 caliber Model 617. This is the stainless steel version of the blued steel Model 17 .22 LR; however, all Model 617's have full under lug barrels. Offered in the same three barrel lengths as the Model 17, the 617 is still in current production and is shipped with rubber grips. The Model 617 is found with a six-shot or ten-shot, steel .22 LR cylinder. The only exception is the early production Model 617-2 which was made with a ten-shot, aluminium alloy .22 LR cylinder. Later "dash 2" 617's were shipped with stainless steel cylinders. Model 53 The Smith & Wesson Model 53 was introduced in 1961 in the .22 Jet caliber. It is a revolver of six round capacity built on the medium K frame using a double action trigger. The .22 Jet cartridge had a listed velocity of 2460 fps using a 40 grain bullet, but actually reached 1700-1800 fps in the revolver. The Model 53 can also fire the .22 Short, Long, and Long rifle cartridges using chamber inserts. The hammer had a two position firing pin to allow it to be switched from rimfire to centerfire as needed. The handgun came with target handgrips and sights and in barrel lengths of 4, 6 and 8.3 inches. In the late 1950s there was considerable interest in the shooting community for revolvers chambered in various .22 caliber wildcat cartridges. Smith & Wesson sought to take advantage of this by unveiling a cartridge known as the .22 Remington CFM (Centerfire Magnum) cartridge or the .22 Remington Jet and chambered a version of the Model 17 in this caliber designating it the Model 53. The Model