I own a Single Six but not the Hunter model. I have not used it on a coyote.

Coyotes are extremely tough and I am sorry to say that I have even lost a few hit with a 22-250 when I was hunting them seriously for their fur... If you shoot enough coyotes it will probably happen. Obviously they were marginal hits or worse.

The gist of my response is that yes the .22 Magnum will work under perfect conditions (ie. heart-lung hit at 100 yards give or take, less is better. I have done it with my .22 Magnum Savage rifle but I keep my shots less than 100 yards. Keep in mind the 7.5" revolver barrel with the barrel cylinder gap will compromise your velocity compared to a rifle, giving even less power.