I'd suggest that your current surname might be a modified version of an earlier name...a "corruption", if you don't mind the term.

It happens...

Guard at Ellis Island: Okay, what's your name, buddy?

Immigrant: Michelangelo Buonaratti...

Guard: That's no name for an American! From now on your name is Mike Boone.

(Source: The National Lampoon Radio Hour)

Seriously, I'd look back in the family records and see if there was another spelling or if it's a corruption of something like McGarrick.

Best

AA