In many ways, the Rheinmetall-Borsig MK 108 30mm cannon was considered to be a masterpiece of weapons engineering, due to it's compact size, ease of manufacture and hitting power. Although it was first designed by Rheinmetall-Borsig in 1940 as a private venture, the design was finalized in 1942. It met a later RLM requirement for a new aircraft cannon that could knock down enemy bombers with the lowest expenditure of ammunition and stay beyond the range of enemy defensive fire.
In short, the MK 108 was a blow-back operated, rear-seared, belt fed 30 mm cannon using electric ignition and was charged and triggered by simple compressed air. One drawback was that once installed, there was no method to adjust the gun's harmonization. One distinctive physical feature was the very short gun barrel, which gave the MK 108 a low muzzle velocity of 500-540 meters (1640-1770 feet) per second. The maximum rate of fire was 650 rounds per minute. The operating sequence for the MK 108 went like this:

An ammunition can fed the rounds to the gun by means of a disintegrating belt
Once the sear was released, the bolt went forward under the action of the two driving springs
A projection on the top of the bolt passed through the ring, thus extracting a round
This then forced the round into the chamber and fired the round while the heavy bolt was still moving forwards
The empty cartridge case reinserted itself in its link after firing
Ejection was achieved by means of pawls activated by camming grooves that were cut into the top of the bolt
Finally, the new round slipped into position and the sequence repeated



ANOTHER BIGGIE BY THE KING

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