They'll ruin your gums and destroy your teeth, but they oughtta be just fine for your barrel.
Levity aside, it sounds as if your "someone" at Springfield has not a clue about these matters. A single FMJ or JHP jacketed in copper/zinc alloy causes a lot more wear than a phsophor-bronze bore brush. Good posts above, all true and all worth heeding.
Scrub away. It's