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The primary purpose of the B-17 Bomber was to deliver bombs to a selected target behind enemy lines. Of course, to do this - the bomber had to be protected in the air from enemy fighters - and this required installing machine guns on-board - operated by gunners trained to do the job. Lets' find out something about the gunners and their equipment before going further.

All aerial gunners were required to attend and complete a gunnery school in order to earn and wear their "Silver Gunner Wings". The school taught men the use of several weapons - firing them both on the ground and in the air from bombers. On the ground some targets were stationary - some moving on tracks while others were shot at by the men while riding in the rear of a pick-up type truck. The primary weapon taught was the 50 cal. machine gun. A man had to learn how to not only fire the weapon - but also to repair the machine gun while in the air. The schools were intense in subjects with each man learning not only his, but other men's lives depended on how well a gunner did his job assignment. Every man on the bomber crew had to know how to fire a machine gun. This included all four Officers and the six Enlisted men on the 10 man bomber crew. The B-17s - Models "F" and "G" were equiped with 13 - 50 cal. machine guns. Two in the "Chin Turret" - Two "Cheek guns for the Navigator - Two guns in the "Top Turret" - One gun mounted in the roof of the Radio Room - Two Guns in the "Ball Turret" - Two guns in the waist fuselage ( one each side ) - and two in the "Tail Gunner's Position".


There are two types of mounts to hold machine guns - one is "Post Mounted" for manually pulling the firing trigger - and the other "Turret Mounted" where the trigger is operated by an electrical solenoid because of the remote location to the gunner. For this writing we will stay with the manually operated firing mechanism.

There are many small parts to a 50 cal machine gun - in fact there are several hundred - however they are assembled into two main functioning sections - one is the exterior housing that includes the barrel holder and the rear main housing complete with belt-feed removable cover - and rear butt plate with handles and trigger mechanism. The second group of parts are the "Guts" - or internal working parts - of the 50 cal gun which are removable - and made-up of the barrel and bolt. On a bomber the housings remain installed in place whereas the internal parts are removed, cleaned and stored apart from the bomber after each combat mission.

Generally - although the Aerial Gunner was capable of cleaning and taking care of his guns - the task was usually taken care of by a Ground Crew of Armorers. The Ground personnel came to the bomber after a combat mission and the crew left for de-briefing - removed the guts of the guns - carried them to a shop where they were cleaned and inspected - and made ready for the next combat mission. Before each mission the guts were delivered to a bomber and left for the gunners to install their own weapons at each gun position.

The hand held trigger mechanism worked the firing of the gun same as was accomplished by an electrical solenoid which moved a lever releasing the firing pin in the bolt. Since both fired a gun the same I will stay with the mechanical firing devise for this presentation. I will say the electrical firing solenoid was used on guns in the "Chin Turret" - the "Top Turret" - and the "Ball Turret" - the other seven guns being fired by direct hand/finger contact.

The 50 cal machine gun was/is an air-cooled weapon - each capable of firing 550 rounds of ammo per minute. The mechanism operated from the recoil of a cartridge being fired. The firing of the cartridge set all internal parts in motion. A cartridge was held in the chamber by a part known as the bolt - the bolt being a "chunk" of steel some 1-1/2 inch X 1-1/2 inch square and about 8 inches in length, weighing about 5 pounds. When the powder in the cartridge explodes several things happen at once - The bullet travels down the barrel - the bolt starts moving reward - a lever sliding in the bolt draws in a new cartridge as the spent casing is expelled - the bolt continues reward compressing a heavy recoil spring - hitting a rear plate which absorbs the pressure by disks located in the rear backplate. As the bolt reaches the rearward most position - the red fiber disks in the back plate compressed along with the spring starts the bolt moving forward - finally bringing in a new cartridge - places it in the bolt shoulders - and inserts it into the barrel chamber ready to fire again. With the trigger still pressed the firing pin moves forward striking the cartridge primer and fires the cartridge - making the weapon fire in automatic over and over as long as the trigger is held to fire. The gunner has been taught to fire an estimated 8 to 10 rounds in a burst to prevent the gun from overheating and melting the barrel. Each gun carried enough ammo in a storage bin for about a minute and a half of firing before the bin must be refilled.

The 50 cal machine gun was accurate for a distance of 1,000 yards - over a half-mile. The weapon would place a bullet pattern of about 3-feet at a distance of 1,000 yards - if placed in a bolt-down devise. However - the vibration of the gun firing cause a slight movement in the gun mounts and the actuall bullet pattern was assumed to be about 30-feet in diameter. Of course - the 50 cal projectal would travel a deadly distance of more than a mile but the pattern was much larger due to vibration of the mounts. Tracer bullets were not an effective method of aiming as the projectal strayed due to the burning of the chemical inside the projectal. Tracers were primarly for effect of letting the enemy know he was being fired upon and nothing more than a warning in some cases.

As I said - the machine gun fired at a rate of 550 rounds per minute - however - some enterprising gunners found a way to increase their fire power ! The red fiber disks in the back plate were of the exact same size as an American quarter - a 25 cent piece - which became valuable in a machine gun. The fiber disks were replaced with American quarters. It required ten dollars worth of quarters to replace the fiber disks in the back platte of each gun. The hardness of the silver coins caused the recoil of the bolt to react quicker - increasing the machine gun fireing rate from 550 rounds to 650 rounds per minute. A gunner so altering the gun in this manner had to be very careful when in combat such that he could overheat his gins much faster than with the fiber disks ! But - the increase in fire power was worth it when enemy fighters made a pass at the formation - and the pass usually lasting on 15 to 30 seconds ! The silver quarters would compress from the beating of the rearward force of the steel bolt - thus the gunner had to always check the quarters for size and replace them when necessary. Necessary being estimated at about every ten combat missions.

( copyright 2001 - See NOTICE on MAIN PAGE )