Denton,

If you search USPTO with Jamison as Inventors Name (IN) you will find (inter alia):

6,675,717
6,678,983

both covering ultra-short rifle cartridges.

At a quick reading I am not sure which claims were infringed by Winchester/Browning or Remington for that matter.

jim

LCDR Jim Dodd, USN (Ret.)
"If you're too busy to hunt, you're too busy."