What exactly is a US Navy MK. 8 GYROSCOPIC Gunsight?

[twocee]

It seems that the Mark 18 gunsight was for use with turret guns, such as installed in the Mariner and Privateer. It was not related to the Mark 8 and was adapted from a British lead computing design. I have found the following in a BuOrd history:

"In October 1942 the Bureau of Ordnance decided to accept the British equipment and use it as the basis for a turret gun sight designated the Mark 18. Unfortunately, the problems of adaptation were greater than they first appeared. Several hundred changes were required.....".

Once the design was finalised, large orders were also placed by the Army, which went on to modify it for use in its fighters, as the Mark 21. Further improvements led to the Navy's Mark 23.

That about exhausts my knowledge of the subject!