RE: .204 or .25 WSSM?
James,
Most people simply look at velocity as the end all, be all of varmint hunting and long range shooting. However, as you stated, sectional density or ballistic coefficient is the single most important thing in ballistics. The longer and skinnier bullet will always outperform the short fat bullet if the weights are the same and you are looking at trajectory and downrange energy/velocity.
Also I would say that the 204 is a much better coyote gun than the 17 rem. I would hesitate to take a shot at a coyote past 300 with my 17 but with the 204......well lets just say it would have to be WAY out there for me to pass it up. Much more devastating (in terms of instant kills) terminal effects with the 204 but same pelt results.