"When we come within the border
we may gar the Cambells claw"

What does the word 'gar' mean in this instance?

"Scour the durk and face the danger
Macintosh has all to do"

What does the phrase 'scour the durk' mean?

Help on this will be much appreciated. I spent over an hour looking for meanings on the www and found nothing there that is other than inconclusive. Thank you.