The historical significance of the “mares leg” was the Henry repeating rifle came out in 1860 and although smith and Wesson started making a cartridge revolver in the 1850’s, colt and most other pistol manufacturers didn’t start producing one until 1870’s due to the smith and Wesson patent on through bore cylinder. There was a very short period of time (civil war through 1860’s) when the vast majority of revolvers available were cap and ball and not quick to reload during a gun fight. In the American west guys would apparently buy a repeating rifle and cut it down so they could carry it like a pistol and have something that could be loaded and reloaded more quickly than a cap and ball revolver. They became pointless after 1873.
In the US the minimum barrel length for all rifles (regardless of semi auto or manual action) is 16”. Lever action rifle companies wanted to sell a short barrelled rifle and customers didn’t want to register their rifles with the ATF as an SBR so they sell them with no stock so they are legally a pistol, not a rifle. The “mares leg” name probably came from a John Wayne movie because that’s what he called it.
