Shamus,

You lucky dog. You have yourself a very nice and rare find. The Halger is a direct descendant of the .280 Ross which has the distinction of being the first 7mm Magnum. Here is an article about the Halger published in the 1984 "Rifle" magazine Issue No. 96:

You may want to copy the images and then blow them up a bit to read them.

Regards,

Buchseman