from information i furnished for the blue book 30th edition. as stated below not all Defender marked revolvers were manufactured by iver johnson but this was.
HANDGUNS SPUR TRIGGER SINGLE ACTION REVOLVER 1873-1899
DEFENDER; INVINCILBE; OLD HICKORY; EAGLE; J.T.JOHNSON; RED HOT; ENCORE; J.S.T. CO.; SMOKER; ENTERPRISE (ENTERPRISE GUN WORKS); LION; TIGER; EUREKA; NAVY FAVORITE; TYCOON; FAVORITE;
SQUARE BUTT MODELS---------------------------------1873-1888
Calibers: small frame .22 rimfire, medium frame .32 rimfire, large frame .38 & .41 rimfire; Barrel length and shape: small frame 2 1/16 inches octagon smooth bore, medium frame 2 15/16 inches octagon with 3 straight grooves, large frame 2 3/8 inches octagon rifled bore (barrel lengths as long as 10 inches have been seen); Weight: small frame 7 ounces. medium frame 10 ounces. large frame 14 ounces.; Cylinder capacity: small frame .22 rimfire 7, medium frame .32 rimfire and large frame .38 & .41 rimfire 5; Height: small frame 2 15/16 inches, medium frame 3 5/16 inches, large frame 3 13/16 inches; Frame length: small frame 3 7/8 inches, medium frame 4 11/16 inches, large frame 5 15/16 inches; Overall length: small frame 5 inches, medium frame 6 ½ inches, large frame 6 3/8 inches;
BIRDS HEAD GRIP MODELS--------------------------------------1873-1888
Calibers: small frame .22 rimfire, medium frame .32 rimfire, large frame .38 & .41 rimfire Barrel length and shape: small frame 2½ inches round smooth bore, medium frame 2 ½ inches 3 straight grooves, large frame 2 7/16 inches rifled bore (barrel lengths as long as 10 inches have been seen); Weight: small frame 6 ¼ ounces. Medium frame 9 ¼ ounces. large frame 13 ¼ ounces.; Cylinder capacity: small frame 7, medium and large frame 5; Height: small frame 2 ¾ inches, medium frame 3 1/8 inches, large frame 3 5/8 inches; Frame length: small frame 3 11/16 inches, medium frame 3 5/8 inches, large frame 4 7/8 inches; Overall length: small frame 5 3/8 inches, medium frame 6 7/8 inches, large frame 6 ¾ inches. Values of both Defender series and other brand names are the same.
*NOTE: Not all spur trigger single action revolver marked with the Defender name were manufactured by Iver Johnson (Johnson & Bye Gunsmith). All of these Brand Names were actually own by J.P. Lovell Co. Before Iver Johnson (Johnson & Bye) started manufacturing revolvers J.P. Lovell Co. had Hopkins & Allen manufacture the Defender (and quite possibility some of the other name associated with Iver Johnson). The main difference in these Hopkins & Allen Defenders is the cylinder locking notches are at the front of the cylinder. The era of manufacture for the Hopkins & Allen manufactured Defenders is 1868 to 1872
VALUE: 100%=$250 60%=$155
DEFENDER 89 SERIES-----------------------------------------1889-1899
Improved version of the older Defender series not sold under any other Brand name. . Square butt and Birds head grip models. Wood and hard rubber grip panels on either butt shape; Caliber: small frame .22 rimfire, medium frame .32 rimfire, large frame .38 & .41 rimfire; Barrel length: small frame 2 1/16 inches, medium frame 2 7/16 inches, large frame 2 3/8 inches; Barrel shape both round and octagon all frame sizes; Weight: small frame 6 5/8 ounces. medium frame 10 3/8 ounces. large frame 14 3/8 ounces.; Cylinder capacity: small frame 7, medium & large frames 5; Height: small frame 2 13/16 inches, medium frame 3 3/16 inches, large frame 3 11/16 inches; Frame length: small frame 3 ½ inches, medium frame 4 5/16 inches, large frame 4 9/16 inches; Overall length: small frame 4 ¾ inches, medium frame 6 ¼ inches, large frame 6 5/8 inches. Frame sizes for the Defender 89 series are the same as the earlier Defender series. (specifications given are for square butt model) The DEFENDER 89 may also be found marked with the same names as the earlier series of single action spur trigger revolvers (see below)
VALUE:100%=$265 60%=$165