He's actually using the HP SS (Super Short) Semiauto, the sparrow is the bolt action. And yeah, with the appropriate ammo it's a very accurate gun. I have the sparrow and have enjoyed it even though it's a non-regulated PCP and does get some vertical stringing action going the more rounds you run through it on a given fill.
Not as easily as I was hoping it might be. Since my pp750 has long since been kaput I tried to see if I could use the reg out of that one and it would almost have worked if the sparrow threaded tube-to-receiver insert hadn't been milled on the inside tube wall. That made getting an oring seal a definite nogo for that particular style regulator..
If you had one of the simple drop in tube reservoir style regulators the right size it might work, would have to get the pressure right though since there's a limited range that the semiauto system functions in.