The ornamental design for a muzzlebrake, as shown and described.
FIG. 1 is a top, front, left perspective view of a muzzle brake showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a top view thereof.
The uneven-length broken line within the shaded area in FIGS. 1 and 3-6 correspond to an unclaimed feature. The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the claimed design. The even-length broken lines showing the remainder of the muzzle brake are for environmental purposes only and form no part of the claimed design.