The Story of the "Pistol Port" on the M4 Sherman Tank

The M4 “Sherman” tank entered production during July 1943 with the D50878 turret casting. The earliest versions of this turret featured a “pistol port” on the left side towards the rear.

Shortly after the tank entered service, users began to report problems with the locking device of the pistol port. On top of that, Ordnance Department tests found the pistol port to be a ballistic weak point. In addition, two areas on the inside right front of the turret casting had been thinned to allow for the proper operation of the traversing mechanism. As the first Shermans entered combat, troops began to report that the enemy aimed for these “thin spots.” As a result of these issues, the D50878 turret was revised in April 1943 to eliminate the pistol port, as well as “increase thickness of turret in area of the traversing mechanism.” Tanks on the production lines, and in depots welded the “pistol port” closed, and it was deleted from the casting. The revised turret castings began to enter the production pipeline around June 1943.

However, the government never actually asked the users what they wanted. In fact, most tank crews in the field liked having the “pistol port”. They just wanted a more reliable locking mechanism. The crews didn't actually use the “pistol port” as a “firing port”. Instead, they found it much more efficient to use the “pistol port” for loading ammunition into the tank. And, as the tank was usually in enemy territory, it was much more convenient and safer for the crew to expel spent casings through the “pistol port” rather than get out of the tank or otherwise expose themselves to enemy fire. After all, having spent casings rolling around and cluttering the small confines of the tank was more than a small inconvenience.

The decision to eliminate the “pistol port” was universally unpopular. The complaints from tank crews in combat areas were quick and unkind. The “pistol port” was quickly added back into the final version of the D50878 turret casting.

The M4 design was constantly undergoing changes to include a number of improvements. In late 1943 the M4 was changed to include the improved D78461 turret casting… which included a return of the “pistol port”.

Sources: http://the.shadock.free.fr/sherman_minutia/m4a4t/transforme_tanks.html