Pressure actuated unloaders are this.. very specifically,
.. by request of every dealer they have in the world..
..cheaper.. SImple as that.
I have HOUNDED AR, Comet, Giant, Suttner, and MTM.. to build one..
We NEED a 4000 psi Flow-Actuated unloader that does NOT cost $500.
A K-7 unloader is flow actuated, but doesn't like doing over 3500psi.. they were designed for 3000.
the K-5 unloader is 3000 psi max, and not rebuildable (affordably).
The Giant version for 4000 psi.. is only good for 4gpm.. that doesn't count fore much.
Pressure Actuated unloaders are especially helpfull in multi-wand systems.
..you can divide flow easily, due to the regulating function of the valve.
otherwise..
Pressure Actuated unloaders are less expensive to build.