I can only speak for corns and gray-bands. My graybands are calmer. Neither species has bitten me except as hatchlings. Then it doesn't hurt, its just funny.

I would think if you handled a wild adult of either species you might get bitten. As far as pain goes, I don't know.

Other species of kings might be more likely to bite than grayband, but I don't know for sure.

I had a 5 foot boa bite me years ago. It was a sudden strike that scared the crap out of me, but it didn't hang on. The bite wound wasn't too bad, maybe a little sore.
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Kent

1.1 Hypo (het lavender, striped) corn snakes, 2010
1.1 Gray-banded king snakes, blairs phase, 2008
3.6 Gray-banded king snakes, 2011
2.1 Oregon rubber boas, w/c 20??