The ornamental design for a modular pistoltransportsystem, as shown and described.
FIG. 1 is a front isometric view of the modular pistol transport system, which embodies my design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is an isometric view thereof; and,
FIG. 7 is an exploded isometric view thereof.
The broken lines in the drawing views represent unclaimed portions of the modular pistol transport system, which are shown for illustration purposes only and form no part of the claimed design.