A muzzle brake for a firearm includes ports bored or otherwise formed into side surfaces of the muzzle brake. The ports may be formed such that a central axis of each port may be present at an angle that is rearward of perpendicular to the through bore. In this manner, the exhaust opening of each port at the muzzle brake side surface is rearward of the intake opening that connects with the through bore. The ports are located in horizontally and symmetrically opposed pairs, one port in each pair extending through a sidewall on opposite sides of a vertical central plane of the muzzle brake. Each port may comprise two parallel bores. A centerline of each boar is tangent to the diameter of the through bore. The bottom of each port bore has a spherical surface 140. This spheroid termination into the through bore and incidental intersection with adjacent ports results acute angles at each edge leading away from the through bore and into the ports.