I found this on another site. Thanks, Bill.
"there were only 450 made in 1941 (A37251-A37700) of this model but an over all production of 237,700.
I.J. MODEL 1900 FIRST MODEL (BLACK POWDER) ----------------1900-1908
Does not have Hammer the Hammer action, solid frame, double action, pull pin cylinder release. Nickel finish standard with blue optional, all barrels are octagon shaped. Offered in three frame sizes and four calibers, grip panels are hard rubber with Owls head logo; Barrel length; small frame 2 ¼ inches, medium & large frame 2 ½ inches, other length barrels were offered at extra charge; Calibers: small frame .22 rimfire with 7 rounds cylinder capacity; medium frame .32 rimfire & centerfire with 5 rounds cylinder capacity, large frame .38 centerfire with 5 rounds cylinder capacity; Weight with standard barrel length: small frame 11 ounces, medium frame 12 ounces, large frame 18 ounces; Height: small frame 3 3/8 inches, medium frame 3 ½ inches, large frame 3 7/8 inches; Frame length: small frame 4 inches, medium frame 4 ¼ inches, large frame 4 7/8 inches; Overall length with standard barrel length: small frame 6 inches, medium frame 6 1/8 inches, large frame 6 ¾ inches. Note: large frame model not introduced until 1903. Between 1900 and 1902 the 38 caliber American Bull Dog frame size was marked as the Model 1900. Will not have letter code prefix to serial number.
DOES NOT HAVE HAMMER THE HAMMER ACTION.
VALUE: 100%=$135 60%=$85 (50% premium for American Bull Dog frame marked Model 1900)
I.J. MODEL 1900 SECOND MODEL (SMOKELESS POWDER)---------1909-1941
Exact same specifications as the First Model except cylinder and internal parts hardened for smokeless powder loads and as listed below. Six shot 32 S&W Long Caliber added to large frame in 1931. All smokeless powder rated Model 1900’s will have a letter code prefix to the serial number. This letter code prefix will be found on the left side of the grip frame (under the grips).
Small frame 7 shot 22 rimfire caliber=D (1909-1917) and A (1918-1941/1942)
Medium frame 5 shot 32 S&W caliber= E (1909-1917) and B (1918-1941/1942)
Large frame 5 shot 38 S&W caliber F (1909-1917) and C (1918-1941/1942) (After 1931 also available as a 6 shot 32 S&W Long)
DOES NOT HAVE HAMMER THE HAMMER ACTION.
VALUE: 100%=$145 60%=$95 (10% premium for 32 Long caliber)
bill"