Space Balls used Calico 22LR rifles...Star wars uded modded Broomhandle...don't think looking at movies is the future view.
I think all pistols and revolvers will be poyl...wait they are almost there already.
Polymer-cased ammunition Ammo
Steyr ACR has 5.56mm NATO/.223 Rem., 7.62mm NATO/.308 Win., 6.8 SPC (6.8x43mm SPC), .300 Win. Mag (.300 Winchester Magnum), .338 Lapua Magnum, and .50 BMG/12.7x99mm NATO ready to go.
http://www.defensereview.com/pcp-amm...take-the-heat/