Colt Walker of Texas had been the major purchaser of the early Paterson Holster Pistol (No. 5 model), a five shot cal .36 revolver, and Samuel Walker became familiar with it during his service as a Texas Ranger. In 1847, Walker was engaged in the Mexican-American War as a captain in the United States Mounted Rifles. He approached Colt, requesting a large revolver to replace the single-shot Aston Johnson holster pistols then in use. The desired .44-.45 caliber revolver would be carried in saddle mounted holsters and would be large enough to dispatch horses as well as enemy soldiers. The Colt Walker
Colt Dragoon Revolver had a comparatively shorter cylinder (thus preventing overloading the cylinder) and held up to 50 grains of powder, whereas the Walker had used up to 60 grains of powder. The Dragoon Revolver had a shorter barrel at 7.5 inches (some later revolvers 8 inches) as compared to the barrel on the Walker. A loading lever latch in front of the lever replaced the spring to keep the lever from dropping during recoil, thereby preventing jamming of the revolver. These variations made the Colt Dragoon Revolver 4 pounds two ounces. These changes also reduced the risks of the Colt Dragoon Revolver