Fofanov says the 125mm's recoil length on the MBT's are at 310mm hard stop, Rh120 is at 500mm (I think, the brochure doc for the gun has really unusual english). But Russian MBT's also don't necessarily have 'strong' suspensions like the NATO mbts and are much lighter. So they dont have to give much care to ground pressure and track size due to their weight being 20+ tons less than the West. And just as said the K2's hydro suspension will help a bit with absorbing the force from firing, just like the Leclerc and admittedly CR2, though watching them fire with the additional weight packages makes them seem like unmovable bunkers instead of 'stable firing platforms'.
It really comes down to how heavy you are which makes it harder to push, how much is being absorbed and how stable you are. Russian tanks don't have a reason to care much for this since they're smaller, tighter, and lighter. Plus with a stabilized sight as with all modern vehicles have, you're not having your eyes forced off target for the next shot.
I'm not sure if strong conclusions can be taken from that one video. Different ammo types produce radically different amounts of recoil. Discarding sabot training ammo doesn't produce too much recoil, while HE-FRAG is firing a big, heavy shell with a lot more momentum.
Aside from that, it occurs to me that the 120mm armed tanks listed are all heavier than the 125mm armed ones, although the weight of the K2 and T-14 overlap.
How a tank responds to the recoil of its gun firing is a function of the total momentum of the shot, the mass of the vehicle, the moment of inertia about the recoil axis (which is affected by which way the turret is facing), suspension stiffness, suspension damping, and recoil system length and forces. You are correct in thinking that the stabilizer doesn't have very much to do with it. In addition, I suspect that the K2 may enjoy very low recoil when firing from a stationary position, as it has adjustable suspension. The rear hydropneumatic stations can be filled with additional gas pressure, which increases the K* of the stations, which reduces the amount that the tank rocks when firing provided the gun is pointed more or less forward.
The most effective way for light vehicles to deal with high trunnion loads from their cannons is to have very long recoil lengths for their cannons' recoil systems, but this comes at a cost. The longer the recoil path of the cannon, the more empty space needs to be reserved to accommodate the movement of the breech. This makes the turret more voluminous and taller.
I don't think that it's a significant cost driver.
*Compressed gas doesn't act exactly like a spring, but close enough.
h44 got a reaction from Sturgeon in The future of PLA bullit spitting devices: Powerful Chinese weapons and infantry units/LEO thread.
