Living on a farm, and being a hunter as well, I've had a "truck gun" for 40 years. My first was a Remington 788 in 243. It was the kind of rifle that could stand up to hard use, and it wasn't expensive, so it didn't matter if it got banged around some. I killed a lot of stuff with it. For some reason or another, I sold it and ended up with an Interarms Mini Mauser in 223. It did the job, until someone figured out I had it in the truck, and stole it. After that, I used a 10-22 for my truck/ATV/tractor/farm rifle for a while. I also used a Ruger 17HMR as well. My current truck gun is a Howa Lightning 20 inch barreled 204. I bought it because I had a bunch of 204 brass and bullets, but I've killed a few coyotes and crows with it. If I was doing it all over again, I'd take a hard look at the Howa Mini in 223. You have a 10 round mag, and a cartridge that will take care of most anything. An AR would be just the thing, if I didn't take some shots from the truck.....but, I don't like that brass being flung on the windshield. Haven't broken one yet, but I don't like taking the chance.