[jonascord]

The Ruger Ranch rifle, while it employs a Garand style gas system, (more like a shrunk M-14 type, with a gas-driven piston hitting the end of the operating rod, which cams the bolt out of lock.) is chambered for the 5.56mm NATO. The AK-74, like all USSR leftovers, is chambered so it can either use Red Army issue ball, or captured NATO ammunition, same as the AK-47 could chamber and function with .308 Nato, and the USSR 82mm mortar could fire the NATO 81mm shell. While they could fire ours, we could not fire USSR issue. As to whether this was worth much is open to debate.
If my side has to depend on scrounged enemy ammo to fight, I'm going to question if I am on the winning side...

[Iris7]

My goodness, what an amazingly erroneous statement. The 7.62x39 in no way is interchangeable with the 7.62x54, nor the 5.56x39 with the 5.7(about)x44.

[Renfield]

"...is chambered for the 5.56mm NATO. The AK-74, like all USSR leftovers, is chambered so it can either use Red Army issue ball, or captured NATO ammunition, same as the AK-47 could chamber and function with .308 Nato, and the USSR 82mm mortar could fire the NATO 81mm shell. While they could fire ours, we could not fire USSR issue...."

You are embarrassing youself here. The AK CANNOT chamber a 7.62 NATO round...it won't even fit into the magazine. And the cartridge head diamater of the Russian 5.45 round is larger than that of the NATO 5.56mm round (it's the same as the 7.62X39 round), so those rounds are not interchangeable either. Where do you come up with this nonsense?

[ought-six]

"The Ruger Ranch rifle, while it employs a Garand style gas system, (more like a shrunk M-14 type, with a gas-driven piston hitting the end of the operating rod, which cams the bolt out of lock.) is chambered for the 5.56mm NATO."

Not quite. The Ruger Ranch Rifle (a Mini-14) fires the .223 Remington round, which is the same caliber as the 5.56 mm NATO round used in M-16s, but the .223 has a slightly less-powerful cartridge. I'd not want to use 5.56 mm NATO rounds in my Ruger Ranch, and in fact Ruger strongly recommends against it.