The .351 Winchester Self-Loading was introduced in 1907 to work with the Model 1907 Self-Loading Rifle. It has been a popular caliber choice for police officers and was a top choice in France’s military during both world wars. The .351 Win can also be used in the Thompson submachine gun, an experimental model designed in 1919 that was never released commercially. The .351 isn’t adequate for deer hunting, but it should perform well enough for bagging mountain lions or coyote. It is best suited for medium sized game hunting because the accuracy is not sufficient for varmints.