Nice review. You really get an idea of how smooth it is.
The real HBAR would be even smoother still; rather then a flash hider it features a compensator designed to push the bipod into the ground for greater stability.
When you also factor in the 42rd mags, it would have been one of the more effective and practical 'Automatic Rifle' mag fed LMG's out there. 42rd would provide 7x 6rd bursts before reloading (studies have shown 6-9rd bursts are the most effective for bipod fired LMG's.)
Shame the Austrians never fielded HBAR's to support their MG42 teams / serve as a Squad level SAW.
Having their MG42/MG3 teams armed with HBAR's would allow their assistant gunners / ammo bearers to provide solid full auto fire when the GPMG is being reloaded, as well as provide LMG fire in another direction in order to prevent flanking / further increase FA fire volume.