Undergunning

Almost as soon as the Peacemaker appeared in .45 Colt, it was also offered in .44-40 as a companion piece to the Winchester Model 1873 rifle, to permit  a man to equip himself with the same ammunition for both his long and short gun.  It startles us today to think that anyone would feel adequately armed with a rifle using pistol ammunition, but Americans had got along for quite a while using the pipsqueak Kentucky rifles, and established a tradition of undergunning that is still with us today.

Jeff Cooper, Guns of the Old West (Boulder: Paladin Press 2008), 22.