Have you seen Time Warp where they test dragon skin body armor?
The narrator says they shoot the vest with a "three-oh-six" rifle. I'm pretty sure it was a "thirty-ot-six" or as commonly read "30-06".
As far as assault rifles of WWII, I've got a couple. My favorite is the Japanese Arisika, type 99 I believe, in 7.7 Jap. The rifle itself is taller than most Japanese, add on the 18"+ bayonet, and you can stick frogs from across the room.
The sights are the best, got a regular peep sight and a folding ladder sight calibrated from like 2 to 15. So I'm guessing it calibrated to either 1500 yards or meters. I spoke to a WWII Marine who said it wasn't uncommon to receive rifle fire from more than a 1000 yards away. I don't know how accurate it was, but I'm sure it kept them on their toes.
There are also two arms about 4 inches long that fold out the side of the ladder sight, both of those are calibrated with a "1" and a "2". I've read that these were used for "leading" aircraft and make accurate hits on passing airplanes. I guess it would work on slower aircraft, but who knows.
My Grandfather had one that he had sporterized with a cheap scope back in like 1954. I know he shot a lot of deer and coyotes with it all his life and it was plenty accurate. He didn't quite shooting it until his quadruple bypass he had when he was like 75. After that, it was 22's only.