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 sizes and locations for machining a 40 m/m barrel.
| Identifier | ExFiles\Box 176\3\ img071 | |
| Date | 20th October 1940 guessed | |
| Sizes and Locations for 40 m/m Barrel. | | Muzzle | Breech | | :--- | :--- | :--- | | Drill | 3.000 dia. 4 point adjustable running steady | 5.000 dia. 4 jaw chuck. | | 1st draw bore. | 2.875 dia. 4 point adaptor. | 5.000 dia. 4 point adjustable running steady | | 2nd draw bore. | 2.875 dia. 4 point adaptor. | 4.325 dia. 4 point adjustable running steady. | | Draw Ream. | 2.875 dia. 4 point adaptor | 4.160 dia. 4 point adjustable running steady. | | Rifling. | 2.875 dia. 4 jaw chuck. | 4.125 dia. 4 point adjustable indexing adaptor. | | ||