Sounds like he is talking bullets, though he refers to them as slugs.... And making .458 bullets out of .40 S&W brass ? I would think is a bit strange.
Edit: Actually found an article on this, they are using ,45 ACP cases to make .458 SOCOM bullets..... Whodathunk....
Author Topic: Making .458 bullets out of .45 ACP cases - 458 SOCOM ...
458socomforums.com › Reloading › Bullets