Is an SMG a rifle

Answer 1

Yes and no. In the early days, a rifle was defined simply as a firearm with a rifled barrel and is intended to be fired from a shoulder. Most submachine guns (SMGs) fulfill both these requirements. However, in modern times, rifles are also characterized by large bottlenecked cartridges (eg. 7.62x51mm, 5.56x45mm, 7.62x39mm), while submachine guns are characterized by the use of pistol cartridges (eg. 9x19mm, .45 ACP). So in most circles, the submachine gun is not considered a rifle.