Apologies in advance, didn't read the whole thread...some parts were a bit boring and to be frank, just stupid and filled with misinformation...but here is my humble thoughts on the subject. First a .308Win. can absolutely do the job with proper shot placement...but I'd rather have a little more bullet in may favor. Secondly, energy is not everything, nor is speed, but diameter (and therefore surface area) and/or weight isn't either. Per my understanding and belief the best cartridges have several features that promote success when ideal conditions aren't present (less than ideal shooting conditions). These include (but are not limited to):
*Bullet Construction-Solids or well constructed expanding ammunition is vital for penetration, which is the key for taking down large dangerous game. Woodleigh bullets (most any), A-Square (most any), Barnes Solids, and Swift A-Frames come to mind.
*Diameter-the larger the diameter (and more importantly frontal area) the greater the crushed tissue, bone, and the better the chances are for hitting a vital organ or deterring mobility (bone and muscle). Frontal area increases exponentially with an increase in diameter so a small change can be important.
*SD (Sectional Density): The greater the mass in relation to the diameter the more it likes to keep on going...penetration is good. An SD of greater than .25 is marginal, .27 is acceptable, and anything more than .29 is good.
*Momentum: Again, it promotes penetration...see a theme here?
*Velocity: Speed Kills...most of the time. When you drive it fast, it takes longer to slow down (when using well constructed bullets that is). Hydrostatic shock is pretty useful in slowing down animals and can cause permanent damage far in excess of directly damaged tissue (but it isn't something that you want to rely on). Over 2000fps is useful, but IIRC 2450fps is about the ideal speed for DG, anything faster is fine, but offers little benefit.
*Energy: Useful, but not unless you can effectively transfer it to the target, a sledgehammer packs a heck of a punch, but won't be very effective if you nail something in the big toe with it. 3k ft-lbs tends to get the job done unless you are looking to drop something big and mean, and a hemisphere away.
The best compromise IMO would be a light, handy, Marlin 1895GG loaded with something heavy (450gr. range is near ideal for this caliber) and fast, a Winchester 1895 .405Win. with a well constructed bullet, or a scattergun loaded with Brenneke Black Magic slugs. All three compromise something in the mix, but are more than adequate with a little practice, and a whole lot easier to tote than a proper DG rifle. To use what you have, I would load up some well constructed bullets in the 180-220gr. range, with a nice stout, but reliable load and a magnum primer for sure ignition. Shoot it enough to ensure it will do the job, before fielding it.
