That behavior is an indication the hammer strike is too light for the current regulator setpoint.
I see you’ve experimented with differing regulator setpoints and hammer strike, and that it’s becoming frustrating. But try it again with a structured approach...
The important thing to recognize is there is only one optimal hammer spring setting for a given regulator setpoint. Too little produces a wide extreme spread. Too much produces an excess muzzle blast, either of which has the potential to impair accuracy.
The good news is, finding this optimal setting is easy. Gradually increase the tension until the velocity no longer increases. Then back it off until the velocity is about 97% of that maximum.
For example, let's say your regulator setpoint is 130 bar and you start gradually adding hammer spring tension. You find the velocity climbs up to 950fps. Meaning if you continue to add more hammer spring tension, the velocity doesn't go any higher. (Note that in some cases, overdriving the valve may cause the velocity to go down, so it's a good idea to gradually step up the HST rather than making huge changes all at once).
So in this hypothetical, it tops out at 950fps. We want 97% of that, or 950*0.97 = 922fps. Back off the HST until it's producing 922fps. Now check accuracy again. If it shows promise, you may then want to try making a small adjustment to the HST to see if it produces a beneficial change to the system harmonics. At that point, it's a trail and error thing but you are starting from a balanced state of tune, and that massively increases your odds of finding its happy place.
Otherwise, try increasing the reg to 140 bar and repeat.
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