This is a shot of the main gun of the F-100 frigates of the Spanish Navy

The Álvaro de Bazán Class, also known as the F-100, includes the most modern frigates of the Spanish Navy, which were entirely built in Spain by Navantia Ferrol.

Harrier II on the take-off ramp of the L-61
A 'Cat' flying over the Pontevedra Estuary

Framed in the 31st Escort Squadron, which has its base in the Arsenal of Ferrol, these frigates have a wide variety of weapons including a mount for launching missiles (with capacity for 48 missiles), two mounts for anti-ship missiles Sub-Harpoon (eight missiles in total), two torpedo launchers (with 12 torpedoes in total), four Browning M-2 machine guns of .50 caliber (12.7 mm), two 20 mm guns and one OTO Melara Mk.45 gun of 127 mm located in the prow, fed with an automatic loader. A few days ago, the Spanish Defense Staff (EMAD) published an interesting video that shows the firing process of the Mk.45, including images of its automatic loader and a slow motion video of the projectile's exit:

In particular, the frigate of the images is the "Cristóbal Colón" F-105, the most modern of the F-100, which entered service in October 2012.