March 10th, 2018: Ruby Loftus

[xoxoxoBruce]

Still don’t think she’s “screwing”, just boring, maybe in advance of “screwing” a buttress (breech-lock) thread, but the trapezoidal is metric.
Ah…

The British Army had first examined the weapon when they received a number of Polish-built examples in 1937 for testing, known as the "QF 40 mm Mark I" (QF standing for "quick firing"), or "Mark I/2" after a minor change to the flash hider. A licence was acquired and the gun was converted from metric to imperial measurements. They also made numerous changes to the design to make it more suitable for mass production, as the original Bofors design was intended to be hand-assembled, and many parts were labeled "file to fit on assembly", requiring many man-hours of work to complete.

I highly doubt Ruby had carbide inserts.