I have seen people use 22lr, 22 mag, 17hmr, 223, 222, 204, 243, 30-06, and so on. What is more important to you, a gun that is only good for coyote, or a gun that can be used for big game also? What is your shooting experience? What is your tolerance to recoil? If you could handle it a 338 Lapua would do the trick out to 1500 Yards lol. But in all seriousness what are the uses for this gun, and such. I have a lot of data and info on different cals but thats a big part before directing you on what to buy. Also a 6.5 x 55 sweede is light on recoil, but huge on take down power, and accuracy. If your looking for a good all around gun go with that, they have enough power to take down a moose, but they are accurate enough well lets just say I won't let mine go and I have 30 rifles.