Lets say we put them up to a challange, Bring 2 Grendels a 16 and 20" standard combat lengths.
with any handloaded or factory ammo the best you or they can make(as hot as you dare but no popping primers). We run gel test on the best bullets of each, We run tests to see which defeats the best body armor and barrier penetration, we do a little long distance accuracy test and we do a reliability and function test in the same 2 rifles of each caliber. It will take a little while to get experts set up to review the gel data the rest should be easy to determine the winner but we need a General or 2 just to watch and someone to film a little.