USS WISCONSIN BB-64
If you will watch how the powder bags are rammed into the powder chamber you will see how accurately the powder bags can be positioned. The gun captain signals the rammer operator when to start and stop the rammer. In the video you will see the gun captain signal for a little more ram and the rammer operator rams the powder bags about 2 inches more into the powder chamber. That shows you how accurately the rammer can be controlled. After the rammer is retracted and the spanning tray removed the gun captain checks to see if the last powder bag is in the right place which is within 6 inches of the mushroom head when the breech plug is closed. The rear of the powder bag which has the red ignition pad must be within 6 inches of the mushroom head or the gun may misfire because the jet of flame that blows through the primer vent in the mushroom head from the combination lock primer may not ignite the primer pad. If the gun captain determines that the last powder bag is too far forward he will reach into the breech and pull the powder bag towards him until it is in the right position before he closes the breech plug.
The primer vent hole is about 1/4" in diameter and extends through the mushroom head for a distance of about 22 inches, so the flame from the combination lock primer must travel a long way to get to the red ignition pad on the powder bag.
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