"That is an interesting argument and it me stop and ponder. I arrived at the decision that you meant the life's total of lead wadcutters you've sent through .357 revolvers, if all gathered up, are HEAVY enough in weight to sink a battleship."
Either way.
Don't over think it, it's just an expression.
I have shot .38 Special wadcutters by the 10s of thousands in .357 revolvers and in my .357 Marlin carbine. Double ended wadcutters, hollow base wadcutters, plated wadcutters, sized and lubed wadcutters, Titegroup, Bullseye, in .38 Special cases, in .357 cases with and without the suppressor in the lever action ................ In fact, I typically load 1000 of them at a time. I have been doing this for probably 30 years. That is a lot of wadcutters.