The AC-130H Spectre (Attack Cargo Plane Project II) currently retired/replaced with the J model Ghostrider. Spectres weapons consisted of twin 20mm cannons (mid pic), one Bofors 40mm cannon and one 105mm Howitzer (bottom pic). See the top pic, there are two black squares that used to house the 20mm cannons. This weapon was removed due to a ricochet issue (collateral damage) reported by Special Forces on the ground, something that has never been mentioned anywhere.
AC-130U SPOOKY II, weapons are a 25mm cannon (automatic), 40mm cannon (automatic as long as it is continuously loaded 4 rounds at a time with one crew member running it) and 105mm howitzer (loaded 1 round at a time with 3 crew members running it). The Spooky II gets its name from the AC-47 of Vietnam, the first Spooky.