The ornamental design for a firearmarm brace sling mount, substantially as shown and described.
FIG. 1 is a perspective view of a firearm arm brace sling mount according to the present invention;
FIG. 2 is a left side elevation view of the firearm arm brace sling mount shown in FIG. 1 which is the same as the right side elevation view;
FIG. 3 is a bottom plan view of the firearm arm brace sling mount shown in FIG. 1 which is the same as the top plan view; and,
FIG. 4 is a front elevation view of the firearm arm brace sling mount shown in FIG. 1.
The evenly spaced broken lines are included to illustrate portions of article; the dot dash broken lines illustrate boundaries of the claimed design; all broken lines form no part of the claimed design.