FIG. 1 is a top perspective view of the muntin bar assembly.
FIG. 2 is a front elevation view thereof.
FIG. 3 is a rear elevation view thereof.
FIG. 4 is a left-side elevation view thereof.
FIG. 5 is a right-side elevation view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The invention pertains to an ornamental design for a muntin bar assembly. The dot-dash-dot lines indicate the bounds of the claimed design, while features shown in dash-dash-dash lines depict portions of the muntin bar assembly that form no part of the claimed design.