As stated I feel that a shotgun with a properly designed slug to PENETRATE should be moderately effective on Buff.The required energy capability seems available from shotshells available.I'd pass on Ele though.No way, no how--

Maybe a 3.5 inch 12" shell with one of the bullet proof "pointed" design slugs specifically for vest penetration that the SWAT entry teams use would give good deep pentration and a large diameter wound track.

I think the solution lies in applying the correct technology to the projectile used to get the penetration desired on Buff.