.308/30-06 is the upper limit of approved rounds at the EBR store. They use a rare-earth magnet from an old disk drive to check for "steel". It's so powerful that even traces of nickel in the jacketing is attracted. Insurance companies say nickel makes the jacket too hard, so it's banned, just like steel cores or jacketing.
Heh, yep, that’s gotta be the magnet that the MDC uses. The Swiss, the Swede, the Ruskie, the Enfield are OK with lead or hunting ammo, noway for mil-surp stuff. Handloading is our friend.