Reduced charge firings (e.g., 2/3 charge) had a correspondingly lower effective charge rating than when a full charge was employed. The relationship was less than linear — a 2/3 charge would reduce wear by more than one third.
The gun captain(?) for a weapon would be responsible for counting the number of firings recorded by the gun as well as the type of charge used. This would be converted into an equivalent number of effective firings, and a resultant loss in muzzle velocity for the gun calculated from the range table data. As time permitted, corrective adjustments might be taken to bring the gun back closer to range table performance when provided nominal ranges. Examples of such adjustments might be to exchange a Dip Strip on an elevation receiver to correct the gun when in director fire, or to alter any ballistic coefficient features available on the gun sight for local laying.
- Email from John Roberts to Tone.
- Admiralty, Gunnery Branch. C.B. 1245. Range Tables for His Majesty's Fleet. Volume I. 1918. (9.2-inch Guns and Above.). Pub. No. OU 6089 (late CB 1245), Vol. 1 The National Archives. ADM 186/236.