Mist, I'm not wrong. The gas system is the system by which the energy from the propellant is diverted to provide energy to activate the system. How the activation occurs is different (but not completely different, as you assert, since all metal parts are forced into motion by the direct action of the propellant gas). You're splitting hairs. The delivery of the energy is the same - unless you propose to get specific and point out tube diameters, lengths, barrel attachment, etc. You're arguing about the nature of the receptacle for accepting the gas.
In other words, the gas systems are the same. They have a clear channel by which propellant gas is captured from the barrel through an open port and diverted to the action so that the action can be operated by the direct force of the gas upon the action. That direct force of the gas moves the bolt carrier on all the rifles I mentioned.
Completely different? Not at all. The gas system is the same. How the bolt unlocks and actuates from the action of the gas is different, but not all that different. The fact that the AR has a rotating bolt and the Ljungman and MAS use a tilting bolt are far more different in operation than the gas systems of the various rifles.
And as I mentioned before, there was no Soviet Kalashnikov concern. Kalashnikov received credit for his design in the model designation AK (plus what ever suffix was added). Izhvesk and to a lesser extent Molot manufactured AK's, as did a slew of other manufacturers in the world. Word had it once that the Maadi was the closest thing to the Soviet AK out there. The Chinese AK's used thicker steel in the receivers. The Bulgarians made some of the best milled-receiver versions.
In any case, a Kalashnikov USA is as close to the original AK as if a company started today with the title "Garand Arms Works" and purported to make the original Garand. Or, as in fact is happening, Rock Ola and Inland making arms (or Springfield, Rock Island Armory, etc.).