The 175mm was designated as a Howitzer because it was not a "Direct Fire" weapon. It was "Separate Loading" which means that the shell was rammed into the forcing cone and then powder bags were put into the breech behind the shell. The charge was "Cut" in that the powder was adjusted to the correct range just like in a 105m or 155mm howitzer. After the breech was closed (interrupted step screw just like the 155mm) a separate primer was attached to the back of the breech and it was fired by pulling a lanyard that tripped a small hammer onto the primer which fired through a touch hole that went through the center of the breech. The "Base Charge" which was the powder bag closest to the breech, had a thin bag of black powder sewn to the bottom of the bag which was ignited by the primer and in turn set off the cordite which was in the main charge. The 175mm had a very short "Tube Life" of about 150 rounds at charge 7 equivalent. This means that if charge 5 were fired a lot, you could get possibly 250 rounds through the tube before erosion wiped out the rifling in front of the forcing ring and ruined the accuracy. We had them on one of our fire bases in Vietnam and as I recall, they didn't sound a whole lot louder than a 155. I used to see Chinooks carrying old shot out tubes out over the Soouth China Sea to drop into the water. Big waste of money as they could have been sent back to Watervliet Arsenal to be re-lined. But then we're talking about a military mindset that used slightly damaged main rotors from Chinooks as sidewalks. Those worked out to about $3 million for about 100 feet of sidewalk.
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