Just watched a video: - YouTube
How heavy are those rounds for the AC130OU?
The aircraft is the AC-130U; there’s is no “O” in there.
Per Lockheed AC-130 - Wikipedia the armament is
Per M102 howitzer - Wikipedia the projectile weighs 33 lbs. I used to have some spent brass from that cannon. The spent brass weighed about 5 lbs. The unfired propellant powder would have been a pound or two. So overall an unfired shell would weigh about 40#.
Is the cannon kind of an aerial howitzer of sorts? I say that because the recoil of the carriage sliding back after loading seems to be similar to the way a standard howitzer artillery piece recoils after firing.
LSLGuy already provided this information in his second Wikipedia link.
It’s an M102 howitzer mounted in an aircraft, so yes, I’d call it an aerial howitzer.
I’ve been aboard AC-130Hs during firing.
There’s a pretty good sidewards jolt when the 105 fires. You can definitely feel the push as the recoil spring compresses then the sharp jerk when it bottoms. Then a wiggle as the whole aircraft flexes and shakes off the vibrations and the aerodynamics realign the airplane with the flightpath after the side forces knocked it out of alignment. They’d typically fire every 10-15 seconds for a half-dozen rounds then pause for a couple minutes for the smoke to clear so they could damage assess or move to a different target. Wham - pause pause pause - Wham - pause pause pause - Wham - pause pause pause - Wham.
The 40’s jolt is much less. Except for the fact it’s a sidewards jolt it’s not unlike the feeling of ordinary chop in an airliner. They tended to fire 3-5 round bursts at about 3/4 second intervals so it was a rhythmic motion. Bump-bump-bump-bump-bump.
The M61s they had at that time just produce an angry buzzing vibration; the felt recoil is pretty minimal.
The installation of the 105 in the aircraft is a pretty minimal mod from the towed 105. The recoil absorption assembly is unchanged AFAIK. The gun had some active elevation control but was fixed in azimuth other than fine-tuning adjustments. They mostly just lifted the gun off the tow trailer & set it onto a similar mount built into the aircraft. The loading was all manual but the firing was electric from the aircraft commander’s yoke switch.