Free: Contests & Raffles.
Who made up that rule?
Only maker I know of that use's copper is Barnes. Hornady and Nosler use gilding metal, same stuff as the jacket's of their other bullet's. How much difference there would be I don't know. Have to pack out the gut's when shot with lead core bullet's? Who made up that rule?
Federal premium likely has 140 gr Barnes. That would do just fine on elk. You can go lighter with copper bullets than what you normally would with lead core since you will get close to 100% weight retention.