Which caliber has the greatest # of commercially available slugs?

I wouldn’t worry too much about how many different slugs are available . I’d go .25 cal because of power requirements for coyote . NSA, VK and Rat sniper slugs have all kinds of weights available which should make just about any head spin . I’d stick to something close to 90 FPE in .25 and get a few sample packets . Find the most accurate and buy a ton of them . 



I enjoy casting , and never run out of ammo . Not to mention I save a pile on shipping .