They are basically M14/Garand rifle carbines. The Garand action and gas system is superior to any gas impingment system. There is a reason ARs have to be constantly cleaned to prevent jams, and took 25 or 30 years to perfect. Mini-14s can shoot the 5.56 NATO as well as the .223 Remington round. I shoot NATO rounds for plinking in my Mini-14 all the time. I would recommend the Mini-30 and the more versatile 7.62X39 round however. I often carry a mini 30 here in the Alaska bush as a long arm, very easy to pack and has plenty of stopping power.
I have a Mini-30 and load my own ammo. I have been able to develop a low-velocity (subsonic) load using 190 grain bullets, which I found to be very accurate at 50 yards, but they won’t stabilize out to 100. What I wanted was something to shoot armadillos in the yard at my farm place at night without disturbing the neighbors. It’s interesting that a round like this, at 1100 ft/second, retains nearly all its muzzle velocity almost out to 100 yards with the high ballistic coefficient of the 190 grain spitzer bullet.
It's not like any M14 I ever fired.
I don't own one, but went over one very closely at the gun shop looking for an M14 like rifle. This was not it.
Now the Springfield Armory M1A is a different story. It is an M14 without semi auto capability.
The Ruger Mini-30 does look like a larger caliber alternative to the Mini-14.
In this video the guy firing his Mini-30 is hitting a target out at 420 yards. Not bad!
http://www.youtube.com/watch?v=n4SVwSGPLOc