PURPOSE: To increase distance in a straight line and shooting range without increasing the rapidity of launching of a spherical bullet.

CONSTITUTION: An opening 2 is formed at the upper part of a barrel for launching a spherical bullet B, where a frictional member 3 which can protrude into the barrel is disposed and a pressing member 4 for pressing the member 3 into the barrel from the outside is provided together with a friction adjusting mechanism 5. The bullet B having been launched makes contact with the member 4 on its way in the moving direction so as to be subjected to the frictional force corresponding to the degree of protusion of the member 4, so that the bullet B is launched from a muzzle of a rifle, while being rotated upwardly.