Base-bleed shells for Royal Navy destroyers

What impact would base-bleed shells have on Second World War vessels such as Tribal-class destroyers using Royal Navy 4.7-inch guns?

They could extend range and improve retained velocity, but reduced explosive filler and poor long-range hit probability leave the practical benefit uncertain.

Base bleed releases gas to reduce drag without providing rocket thrust, allowing a shell to retain more velocity. The gas-producing equipment takes space that could otherwise hold explosive filler. A general extra-range figure of five to fifteen kilometres is raised, but the discussion does not establish that performance for a particular 4.7-inch shell. At the longest ranges, destroyer gunfire would have very little chance of hitting. Retaining velocity at shorter distances might instead improve armour penetration, with Mediterranean Tribal-class encounters against Condottieri cruisers offered as a possible application. That benefit remains theoretical, and the practical tradeoff is unresolved.