Scandia did not determine the gun was over rammed. That was obvious from the first day of the investigation. Scandias test methodology used to create a spontanious detonation of a powder bag cannot be duplicated in a MK VII gun. They tinkered the with trim layer in a powder bag then hoisted it to various heights with crane then dropped the bag onto a concrete slab. they got one bag to detonate out of over a hundred tests. The Navy’s conclusion that Hartwig intentionally over rammed the load, was circumstantian at best, and could not be proven. However, he was the gun captain, and he was the man that controlled the ramming of the projo and powder.
A 16-inch turret internally is divided into four sections: the turret officer's booth and three gun houses. The gun houses are separated from each other and the turret officer's booth by flameproof bulkheads and doors. Each gun house contains four men: gun captain (plugman), powder hoist operator, cradle operator, and rammerman.
Each gun house is its own world composed of the plugman (gun captain) who opens and closes the breech plug of the gun, wipes the face of the breech plug clean after each shot, and inserts the combination electric-percussion primer (they resemble a brass shotgun shell) in the plug's firing lock prior to firing, and is in overall charge.
The cradle operator controls the cradle and spanning tray for the projectile and powder bags.
The powder hoist operator controls the powder hoist and powder hoist door.
The rammerman controls the actual ramming of the projectile and powder bags (two loads of three 110 lb. bags) into the gun chamber for a total of 660 lbs. of powder.
To load, the gun goes to 5 degrees. The plugman (gun captain) lowers the breech plug and that initiates a blast of high pressure air into the gun chamber to physically blowout any residual embers or powder bag residue. After the gun captain visually verifies a clear bore and wipes the breech plug face of any firing residue, he orders the projectile loaded.
The projectile is at the top of the shell hoist and supported by the cradle. The cradle operator pushes the button to lower the cradle and extend the spanner tray. The gun captain orders the projectile rammed and the rammerman extends the rammer chain to push and seat the projectile into the end of the gun chamber. The rammerman retracts the rammer, ready for powder bag loading.
With the powder car loaded with six bags of powder and at the ready position (UP), the powder hoist operator opens the hoist door and three powder bags are ejected onto the tray. The hoist operator closes the door and the hoist cycles to bring the second set of powder bags for loading.
The hoist operator verifies the RED dyed end of each powder bag (ignition pad) all face way from the gun breech. The gun captain orders the first load of powder bags rammed. The rammerman extends the rammer to insert the first three bags of powder into the breech so the leading bag rests against the base of the projectile. The rammerman retracts the rammer.
The powder hoist operator opens the hoist door to eject the second set of powder bags onto the tray, closes the door and the hoist powder car returns to the powder handling room for reloading. The hoist operator visually checks the powder bags so each RED dyed pad on the powder bags face away from the breech.
The gun captain orders the second load of powder bags rammed. The rammerman extends the rammer to push the second group of three powder bags into the gun chamber. The stroke is adjusted so the top of the third bag touches the ignition pad of the fourth bag in the chamber (as referenced to the face of the chamber). The rammerman retracts the rammer.
The gun captain orders the cradle retracted and the cradle operator pushes the button to raise the cradle and retract the spanner tray. When the cradle is in its fully UP position, the projectile hoist brings a new projectile for loading. The gun captain inserts the combination primer into the breech plug firing lock and closes the lock to assure electrical contact by the firing pin. The 16-inch gun is now ready to fire when the trigger is closed in the turret officer's booth or by main battery fire control.
The rammerman controls the length of the rammer chain stroke to load the projectile, first and second sets of powder bags. The length of stroke is adjustable and the rammerman references an indicator that tells him the length of the stroke. If he misreads the indicator or slips up and does not remember the number of bags already loaded, he will get an over-ram of the powder bags. This can (and has) produced enough internal friction within the powder bags’ stacked propellant sticks to cause ignition of the powder. The result is a flash back of 660 lbs. of burning propellant and certain death for the gun house crew.
The Navy knew this condition was possible on the 16”/50 guns of the Iowa-class because they had duplicated the over-ram flashback condition on a Baltimore-class 8”/55 bag gun.