These models are similar to the one you are viewing.
.38 centerfire cal., 5 shot, 3 1/4 in. barrel, nickel finish, hard rubber grip panels with owl's head at top, marked on barrel top rib with patent dates and "Iver Johnson Co. Worchester Mass." marked on barrel top strap, with model name "SWIFT", does not have hammer the hammer action, only sold through J.P. Lovell Co., 16 7/8 - 17 7/8 oz. Mfg. 1890-1894.
.22 rimfire, .32 or .38 centerfire cal., large or small frame, blue or nickel finish, 5 or 7 shot, 3 or 3 1/4 in. barrel (5 in. barrels have been seen), does not have hammer the hammer action, safety notch on hammer, hard rubber grips with U.S. at top, oversized two piece hard rubber grips optional, brand name revolver mfg. by Iver Johnson's Arms & Cycle Works sold through the wholesale trade, never listed in any IJ catalog, although it was listed in some European catalogs as an original Iver Johnson product, main ser. no. located on left side of grip frame, 12-17 3/4 oz. Mfg. 1910-1935.
same model as the U.S. Revolver Co., except for markings on the barrel, large and small frame, does not have hammer the hammer action, top of barrel marked for .38 SMITH & WESSON cartridge" (or .32 for small frame), and "SECRET SERVICE SPECIAL" on left side of barrel, main ser. no. location on left side of grip frame, mfg. for Fred Biffar Co. of Chicago., four other companies also manufactured this gun - Meriden Firearms Co., Hopkins & Allen Firearms Co., H&R Arms Co., and an unknown Spanish company. Mfg. 1912-disc.
.22 rimfire, .32 centerfire, or .38 centerfire cal., nickel (standard) or blue finish, hard rubber grips with owl's head design, small or large frame, 5 or 7 shot, 3 (small) or 3 1/4 in. barrel, single top post barrel latch (release lever mounted on left side of top strap), flat leaf hammer spring, first revolver marked "Iver Johnson's Arms & Cycle Works", some early models were marked "Iver Johnson & Co.", uses hammer the hammer action, main ser. no. location on left side of grip frame, 12-17 1/4 oz. Mfg. 1894-1895.
.22 rimfire, .32 centerfire, or .38 centerfire cal., 5 or 7 shot, small or large frame, 3 or 3 1/4 in. barrel, hard rubber grips with owl's head on top, optional oversized wood or hard rubber grips, all coil springs, redesigned model for smokeless powder, double top post barrel latch, hammer the hammer action, coil hammer spring, four cross pins in lower frame, main ser. no. located on left side of grip frame, 13 1/2 - 19 1/4 oz. Mfg. 1909-1941.