Me and my friends do a lot of varmit calling here in mts of AZ, and there is a lot of different situations which may call for different ideas and guns. First let me say any good flat shooting rifle will work and the 257 is no exception. I used a 270 for years and both make a good all around choice for a multipurpose gun. I finally settled on a 243 win shooting 60 gr hp @ 3800 fps or 55 gr sp @ 4000 fps, these are stiff loads, but will dump a dog like right now if you hit it right. The last bobcat I shot was with a 270 and like to tore him in 3 pieces, pelt was destroyed. My very good friend uses an old savage 24 combo gun 12 ga/223. It's a very good idea if you hunt in thick and open areas while walking around. Another rifle I use is an ar-15 with a burris b-plex and is dead on to 500 yds, this is great for multiple dogs coming in at the same time. OK I know it sounds bad, but it works. One situation where I would recommend a heavier calber such as a 257 or 270 is where we live we have a lot of mtn lions, bear and a few mexican gray wolves, the wolves are protected, several times I have called in lion and bear, I didn't shoot them just sat and watched, pretty cool, but makes me wonder just how many times I didn't see them, especially the cats, very sneeky. Anyway one of these days I will dump one. A friend of mine shot a lion a couple yrs ago while calling , had the call in a bush, hit the call and the cat, got very excited, got the cat stuffed and still hasn't got a new call. Another younger friend shot a mtn lion in the head at 12 ft with a bow which snuck in on him while elk hunting last yr, this cat was going to attack, he was very lucky. If I had to choose a long range howler gun it would probably be a 243, 6mm, 240 WBY, 257 or 270 but the last 2 are a little on the heavy side for my likeing, but if it works it works. PS when I do go into lion country I always carry a hot 10mm auto as back-up. Good luck on your choice.