What is claimed is the ornamental design for a firearm muzzle brake device, as shown and described.
FIG. 1 shows an isometric view of a fireman muzzle brake device.
FIG. 2 shows a front elevation view of a firearm muzzle brake device.
FIG. 3 shows a back elevation view of a firearm muzzle brake device.
FIG. 4 shows a right side plan view, which is identical to a left side plan view, of a firearm muzzle brake device; and,
FIG. 5 shows a top plan view, which is identical to a bottom plan view, of a firearm muzzle brake device.
The outermost and innermost broken lines in FIG. 3 depict the boundaries of the claim and form no part of the claimed design. The other broken lines depict portions of the fireman muzzle brake device that form no part of the claimed design.