A muzzle stabilizer for a repeating firearm is described. The muzzle stabilizer includes a tubular body having two or more gas vents for venting gas in an average direction that exerts a corrective force for counterbalancing muzzle climb during periods of repeating discharges. An attachment flange, which has a coupler adapted to mate with a corresponding coupler on the end of the muzzle of the firearm, is disposed at a first end of the tubular body. A gas regulator is engaged with a second end of the tubular body for adjusting the venting of gas through at least one of the gas vents. The gas vents can include a plurality of ninety-degree vents of graduated sizes radially arranged about the tubular body. The muzzle stabilizer can include a multistage expansion chamber through which high pressure and temperature gas expands before it is vented through the gas vents.