The helmet was set into place and fastened to a heavy clavicle locking ring on the metallic suit.
The bolt head, locking ring, and extractor and magazines were also revised to work with the increased size and operating pressures of magnum rifle cartridges.
Into the above mentioned locking ring, the bolt locks by rotation; thus, the receiver with locking ring, bolt and barrel form the breech of the rifle.
Two were produced in the original "Old FD" style with a silver locking ring for the breech lock mount at the base, while three models were produced as "New FD" lenses where the entire lens barrel rotated to lock the lens in place.
Rendering safe a type 17 fuze was normally a simple and straightforward process i.e. unscrew the fuze locking ring, remove the fuze from its pocket in the side of the bomb and unscrew the gaine.
It is distinguished by its three-pronged flange, which can be oriented in any of three positions and is held in place with a friction locking ring.
This gun included a smaller chamber, a shell-centering cone, a single-slope band seat, uniform rifling, and a tube locking ring.
The mount is locked into place using a friction locking ring which, in conjunction with the four prongs of the flange, creates a very strong lens seating.
The original generation of FD lenses featured a silver coloured locking ring at the base.
