Was just researching calibers that give tou serious knockdown power.
Two things came to mins:
1. Serious: the problem is bullet selection more than caliber, the edge is very capable aslong you use the right bullet, you could get a boutique bullet maker to make you exactly what you want, rather than having entire another rifle built.
2. Not-so-serious: have you looked at the 950 JDJ? Shoots a 3300grain pill (over half a pound) at something like 2800fps or faster. About 40000ft/lbs of energy
it's a necked down 20mm Vulcan casing