A simple trick for improving the 76mm ready racks in the M4 Sherman from Army Motors, February 1945:
Releasing 76mm Shells for Active Duty
UPSIDE-DOWNING YOUR TANK’S READY RACK AND SNAPPING OFF THOSE CLIPS IS WHAT DOES IT
If the 76mm, six-round ready rack or four-round ready rack on your medium tank (in the turret near the gunner’s seat) looks like the one shown in Fig. 1, here’s a simple fix to loosen the ammo.
The end clips (arrow in Fig. 1) hold the shells in the rack good and tight—too tight for fast unloading. So, loosen the top screw and remove the ammo container from the box (Fig. 2). Snap off the clips by bending them back and forth with a pair of pliers or cut the rivets with a sharp chisel. Then turn the box upside down, so the shell holes that were on top are now on the bottom, and slide it back into the rack (Fig. 3).
This is the important thing because inside the shell container there’s a spring that presses down on the shell, holding it firmly. That’s what makes the shell so hard to get out. When the box is turned over, the shell presses on the spring—the pressure’s gone and you can unload lots faster.
There’re several types of six-round ready racks (76mm), so be sure you work this only on the type rack that’s pictured.