I use several different guns for coyotes, pretty much anything that I feel like using. I've got four dedicated varmint rifles, but I'll use any of the list below during any given year:

Bushmaster AR-15A4 Stainless target rifle .223 with a 6.5-20x42mm Nikon. (I've got two other AR's that I commonly use for coyotes)

Savage 12FVSS with skeletonized Dragnov target stock .22-250 wth a 6-24x42mm Leup.
Winchester Coyote in .223WSM with Laminated wood stock with 4-16x42mm Nikon
Remington 700PSS .308win with 6.5-20x42mm Nikon

Ruger Single Six .32H&R mag Stainless birdshead 4 5/8"

Savage combo gun .222 over 20ga with Williams receiver peep rear and globe frontsight

Marlin Mod 60 .22lr semiautomatic with 3-9x40mm Bushnell.

Ruger Mark II .22semiautomatic pistol

I also use basically any other gun I feel like...I've even used my CZ550 .416Rigby and a .45-70 Marlin 1895 Cowboy for coyotes.