Abstract: A dually-adjustable device for firearms is provided which is attached to the muzzle of a firearm to stabilize the muzzle and to suppress the flash during firing. The device is dually adjustable to counter both the magnitude and direction of firing forces. The device is further adjustable to individual firing characteristics as well as varying powder loads in ammunition. The device includes a cylindrical-shaped main body with at least one surface opening. One end of the main body attaches to the muzzle; the main body can be rotated about the longitudinal axis of the muzzle. The device further includes a cap with a gas-restricting opening which attaches to the other end of the main body. This gas-restricting opening in the cap causes a portion of firing gases to back up and flow through the surface opening thereby causing force in the direction of the opening which serves to stabilize the muzzle. A preferred cap comprises a frustum-shaped portion which narrows towards the firearm.