OK, checked speeds with regulator set at what looks like 140-145 bar. Power Wheel at MAX and valve on 4.
Hi: 857 fps
Low: 829 fps
Ave: 842
ES: 28
SD: 7
Still not great, but the Heavies MK I grouped great.
At 30 yes (where I zero) two 5-shot groups measured 3/8" and 1/4" respectively. I shot a couple of groups at 50 and both groups were 3/4". I have less than 100 shots through the rifle and am sure things will get better after break in. I think that the regulator will break in and ES will get better. But I'm happy with the accuracy. Not as fast as hoped for but you adjust velocity to maximize accuracy so I might be there.