Greetings,
Looks homemade. One thing of interest is the spring that pushes the sliding insert in one direction removing the backlash from the screw thread. The maker was thinking when he/she machined it.
Adjustable bars are handy for load development. For making a run of match ammo, a fixed bar or one with a bushing is my preference as there is nothing to come loose.
Also, as the weather changes, you will be prompted to "tweak" the adjustable bar to compensate for atmospheric changes.
Cheers,
Dave
