the copper (or aluminum) ring is not a primitive flat washer but so-called sealing washer (or ring joint gasket). it is as electrically conductive as the body tube, that's why you could think of it as extension of the tube.
now you have a longer tube.
A longer tube can host longer cells.
Protected 10440's are such longer cells :D
( i havent received *any* 10440's yet (DX), so i cant confirm if the gasket theory works out fine lol. it's an idea which i stole from a German forum where kreisler is banned because of exemplary bashing and shilling lol )
If you dont plan to feed 10440's, then never mind.