So in 1943 158 was 850 fps. Today most makers say that's a +P load.
During World War II, some U.S. aircrew (primarily Navy and Marine Corps) were issued .38 Special S&W Victory revolvers as sidearms in the event of a forced landing. In May 1943, a new .38 Special cartridge with a 158 grains (10.2 g), full-steel-jacketed, copper flash-coated bullet meeting the requirements of the rules of land warfare was developed at Springfield Armory and adopted for the Smith & Wesson revolvers.[18] The new military .38 Special loading propelled its 158 grains (10.2 g) bullet at a standard 850 ft/s (260 m/s) from a 4-inch (100 mm) revolver barrel.[18] During the war, many U.S. naval and marine aircrew were also issued red-tipped .38 Special tracer rounds using either a 120 or 158 gr (7.8 or 10.2 g) bullet for emergency signaling purposes.[18]
"In 1956, the U.S. Air Force adopted the Cartridge, Caliber .38, Ball M41, a military variant of the .38 Special cartridge designed to conform to the rules of land warfare. The original .38 M41 ball cartridge used a 130-grain full-metal-jacketed bullet, and was loaded to an average pressure of only 13,000 pounds per square inch (90 MPa), giving a muzzle velocity of approximately 725 ft/s (221 m/s) from a 4-inch (100 mm) barrel.[19][20] This ammunition was intended to prolong the life of S&W M12 and Colt Aircrewman revolvers equipped with aluminum cylinders and frames, which were prone to stress fractures when fired with standard .38 ammunition. By 1961, a slightly revised M41 .38 cartridge specification known as the Cartridge, Caliber .38 Ball, Special, M41 had been adopted for U.S. armed forces using .38 Special caliber handguns.[20] The new M41 Special cartridge used a 130-grain FMJ bullet loaded to a maximum allowable pressure of 16,000 psi (110,000 kPa) for a velocity of approximately 950 ft/s (290 m/s) in a solid 6-inch (150 mm) test barrel, and about 750 ft/s (230 m/s) from a 4-inch (100 mm) revolver barrel.[21][22] The M41 ball cartridge was first used in .38 revolvers carried by USAF aircrew and Strategic Air Command security police, and by 1961 was in use by the U.S. Army for security police, dog handlers, and other personnel equipped with .38 Special caliber revolvers.[22] A variant of the standard M41 cartridge with a semi-pointed, unjacketed lead bullet was later adopted for CONUS (Continental United States) police and security personnel.[20]
A request for more powerful .38 Special ammunition for use by Air Police and security personnel resulted in the Caliber .38 Special, Ball, PGU-12/B High Velocity cartridge.[21] Issued only by the U.S. Air Force, the PGU-12/B had a greatly increased maximum allowable pressure rating of 20,000 psi, sufficient to propel a 130-grain FMJ bullet at 1,125 ft/s (343 m/s) from a solid 6-inch (150 mm) test barrel, and about 950–980 ft/s from a 4-inch (100 mm) revolver barrel.[21] The PGU-12/B High Velocity cartridge differs from M41 Special ammunition in two important respects—the PGU-12/B is a much higher-pressure cartridge, with a bullet deeply set and crimped into the cartridge case.
