The .38 Long Colt (commonly known as .38 LC) [9.1 x 26mm] is a black powder cartridge introduced by Colt's Manufacturing Company in 1875, and was adopted as a standard military pistol cartridge by the United States Army in 1892 for the Colt New Army M1892 Revolver. It is slightly more powerful than the .38 Short Colt, or .38 SC. The .38 SC and .38 LC differ in case length, and in bullet diameter, weight, and design.
The .38 Long Colt's predecessor, the .38 Short Colt, used a heeled bullet of 130 grains (8.4 g) at a nominal 770 ft/s (230 m/s), producing 165 ft·lbf (224 J) muzzle energy. The cylindrical "shank" or "bearing surface" of the bullet, just in front of the cartridge case mouth, is .374 or .375 in (9.50 or 9.53 mm) in diameter, the same as the cartridge case (exactly like the .22 rimfire cartridges). A smaller-diameter portion of the bullet, the "heel", is crimped inside the case mouth, and the lubricant is outside the case, and exposed.
In contrast, the .38 Long Colt uses a .357–.358 in (9.07–9.09 mm) bullet, the bearing surface and lubricant of which are entirely contained within the cartridge case. This keeps the waxy lubricant from collecting grit which can damage the revolver's barrel. Colt, however, retained the single-diameter charge hole, so the bullet was grossly undersize as it traveled through the chamber throat. It was supposed to expand in the throat and be "swaged down", or reduced again in diameter, as it entered the barrel, but expanded unevenly producing poor accuracy. Velocity was the same 770 ft/s (230 m/s), but bullets weighed 150 grains (9.7 g), resulting in a muzzle energy of 198 ft·lbf (268 J).
The cartridge's relatively poor ballistics were highlighted during the Philippine–American War of 1899–1902, when reports from U.S. Army officers were received regarding the .38 bullet's inability to stop charges of frenzied Moro juramentados in the Moro Rebellion, even at extremely close ranges. A typical instance occurred in 1905 and was later recounted by Col. Louis A. LaGarde:
Antonio Caspi, a prisoner on the island of Samar, P.I. attempted escape on Oct. 26, 1905. He was shot four times at close range in a hand-to-hand encounter by a .38 Colt's revolver loaded with U.S. Army regulation ammunition. He was finally stunned by a blow on the forehead from the butt end of a Springfield carbine.
Col. LaGarde noted Caspi's wounds were fairly well-placed: three bullets entered the chest, perforating the lungs. One passed through the body, one lodged near the back and the other lodged in subcutaneous tissue. The fourth round went though the right hand and exited through the forearm.
As an emergency response to the round's unexpectedly dismal performance, the U.S. Army authorized officers to carry M1873 Colt Single Action Army revolvers, chambered in .45 Colt, and issued from reserve stocks. Army Ordnance also purchased a number of M1902 revolvers (the M1902 was actually Colt's New Double Action Army Model 1878, a .45-caliber rod-ejector double-action revolver) for issue to officers deploying overseas.
The .38 Long Colt remained in service until 1909, when the .45 M1909 cartridge was issued along with the .45 Colt New Service revolver as the new standard military sidearm for the U.S. Army.
In civilian use, the .38 LC was chambered in a number of Colt revolvers and saw some use among target shooters. Various U.S. police forces also adopted the cartridge. However, the cartridge became nearly extinct after Smith & Wesson's more powerful .38 Special cartridge became widely popular as a civilian and police service cartridge. By 1908, even Colt was chambering their new Police Positive and New Army revolvers in ".38 Colt Special", which was nothing more than the standard .38 Smith & Wesson Special with a different headstamp.