Here are two pictures of a restored B-25H Mitchell Medium Bomber
The first WWII B-25's to hit the streets were woefully undergunned. In the pacific theater, many squadrons performed in-the-field upgrades of armament. They'd scrounge .50 cals and tack them on anyplace they could manages. Some versions eventually had as many as 12 .50's firing in the flight direction. That's eight in the nose and another four in either side in a pair of conformal pods.
The Army and Mitchell eventually collaborated on bring the mods into production and turned transformed the B-25 Mitchell from a medium bomber into an angel of death. They went from dropping a few thousand pounds of bombs and praying that they'd get back to the base without being shot out of the air to being one of the most feared anti-shipping aircraft of WWII.
The H model shown below has four .50 cal machine guns and a 75mm cannon in the nose.
B-25s were flown by the USAAF, USN, and USMC, as well as a dozen or more allied forces during WWII.
Needless to say, the Mitchell is one of my favorite aircraft.