The result is the 6.5 WBY RPM. Weatherby lengthened the .284 Winchester case and gave it a rebated base (i.e., the base of the cartridge is narrower than the case). That allows the gunmaker to use a smaller bolt face and a smaller bolt, but the case itself can still be of a magnum diameter. That means there’s room for a magnum amount of propellant. If there’s a downside to rebated cases, it’s that they have a reputation for extraction issues. The extraction claw has slightly less face to latch on to, pull, and eject. Still, rebated cases are nothing new. If you’ve ever shot a Remington Ultra Mag or Winchester Short Mag, you’ve extracted a rebated case.