From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Table of specifications for various stages of 40 m/m barrel manufacturing.
| Identifier | ExFiles\Box 175\3\ img231 | |
| Date | 20th October 1940 guessed | |
| Sizes and Locations for 40 m/m Barrel. Drill 1st draw bore. 2nd draw bore. Draw Ream. Rifling. Muzzle 3.000 dia. 4 point adjustable running steady 2.875 dia. 4 point adaptor. 2.875 dia. 4 point adaptor. 2.875 dia. 4 jaw chuck. Breech 5.000 dia. 4 jaw chuck. 5.000 dia. 4 point adjustable running steady 4.325 dia. 4 point adjustable running steady. 4.160 dia. 4 point adjustable running steady. 4.125 dia. 4 point adjustable indexing adaptor. | ||