I mostly call with a DPMS Prairie Panther in 223. It is a picky sucker but shoots RAM reman ammo with a 55gr V max at 2964fps really well. I've fed it a lot higher priced ammo but it doesn't like anything else as well as this. It has a Leupold VX-3 3.5-10x on it and a Jard 2lb trigger.
When range or wind makes me think it's a good idea I step up to a custom 243 bolt action. It's built with a Ruger action, McMillian Gamescout stock, Pac Nor #4 fluted barrel, Timney 2lb trigger, and a Vortex Viper PST 4-16x44 scope. Right now I'm experimenting with the Hornady Superformance 58gr V max ammo in it. I got a box last week and it shot really well from the bench. This rifle had not shot anything under 85gr well before I tried this. I will see how it does on coyotes. The 85gr Sierra or Speer bullets are hard on them.
My favorite truck gun is an old Sako L579 243 I bought used a while back. Someone else had used it as a truck gun for a good long while, it's not the prettiest Sako I've ever seen by a ways. I had it bedded, floated, and the trigger set to 2lbs. It has a 4.5-14x Leupold VX-III on it with the VH reticle. It seems to like everything I feed it. Currently I'm shooting the 69gr Berger Varmint bullet.