Speaking as a native Scot, his accent wanders a bit more than Doohan's (which at least stayed consisten throughout the series before turning Irish in the movies) but is more Scottish, and he plays it with a more Scottish attitude IMO - "Get tae f-" is *exactly* how I'd have reacted at the same moment, and I don't believe for a second that that line was in O&K's script...
But no-one in Scotland talks like Simon Pegg's mash-up of Scottish accents.
On both - I loved the accent and it was far more authentic than some Scots manage on TV or film.
Even I have to ham my accent up to get a native crowd to believe I'm anything but American as I'm to 'middle class' to be taken seriously, according to feedback.
The 'Get tae' line was far more genuine than anything I've tried and he does sound like the Scots I know that have lived one place then moved to Glasgow.