Not trying to start anything, but as a progressive, my take on gun issues has less than zero affect on what the military needs to do their job. I support whatever gives the women and men out there on the pointy end of the spear the best chance to come home. I love Javelin. Best thing for infantry since sliced bread.
Effective wise I think the M16/4 platform is an ergonomic atrocity and the 5.56 is a poor cartridge that is best used on wood chucks and watermelons.
I also think you are never going to get past the technology disconnect between a bullet that expand and kills cleanly (human or animals) and one that you want to poke holes though things that resist it (armor, walls, bricks etc) - 7.62 ball just leaves a slightly bigger hole. The day someone figure out a bullet that adjust itself to what its hit is going to be a fine one.
What hopefully come out of this is a ammo that is close to 5.56 in weight and has the ballistics to be effective out to 800-1000 yards (which means it works fine under that)
The real world says you won't alwyas have mortars or air support to deal with a guy behind a rock with a rifle 1000 yard out and the boots on the ground have to handle it.