Terry,
when you tried this, what results were you getting with 60 ft.lbs?
Worse than when I wound down the rifle to 38 ft.lbs., mate.
I was using Bisley Magnums, graded, sorted and individually weighed - yes, it's tragic but so am I when I'm in 'nth-degree' mode.
My average 10-shot groups at 100 yards, shot indoors with 60 ft.lbs. measured just under 3 inches. As I say, some pellets landed on top of each other, but others veered off to all points around the 1 inch disc target, sometimes by as much as 6 inches.
Outdoors, using range flags every 10 yards to assess the wind, those 'rogue' pellets would often miss by a foot, when I could feel or see not a trace of wind. Most frustrating, I can tell you.
I can spin, draw and fire with my walther cp88 and get a 1 inch group at 200 yards.
Daystate mk3 RT with Bushnell Trophy 6-18x40
Recommended deals with: mrfixit, Steve83, Merlyn, johnyjohnjonno
At the muzzle, less than 10 f.p.s. At the target, often double that outdoors. I used regulated and non-regulated rifles, springers and gas-rams. Incidently, the two occasions I clamped the precharged rifles' actions to a rig, the groups actually got worse.
As so often happens, there are more questions than answers, mate.