Highly doubtful, all the Cats I`ve seen in museums have the ammo canisters mounted in a rack on the bulkhead immediately forward of the blister – in arms length of the gunner. The next compartment forward was the sleeping quarters with four bunks and not a lot of room for storing ammo canisters.
The Cats in RAAF service had the 50s belt fed from a large ammo box mounted on the walkway between the guns.
Simmo