This article is from the Vietnam FAQ, by Brian Ross, John R. Tegtmeier, Edwin E. Moise, Frank Vaughan, John Tegtmeier with numerous contributions by others.
All weapons EXCEPT the 105mm were fixed. We did have the capability
of changing their positions while in flight, but is made no sense to
do so. It was easier to move the aircraft. The 105MM had to be moved
as the large muzzle-blast diffuser extended below the landing gear if
left in the firing position. so we cranked the 105MM down after every
take-off, and cranked it up before landing. I don't ever recall
changing the position of any other gun, as it was unnecessary. The
fire control system could compensate for the exact firing angle. This
is one reason why we used to try and go to a "relatively" safe area to
boresight our guns at the beginning of each mission.
 
Continue to: