Yes he did --- in both editions of Power Without Powder (there were two different editions) Mike recommended opening the HW80 transfer port out.
As good as Trigger to Muzzle is and how revolutionary it was when first released in 1976 you need to bare in mind that a lot has changed in 37 years.
In 1976 calculators were in their infancy --- 1977 being the first year they were deemed good enough to use them in O level exams.
Decent cheep chronographs were unheard of.
Digital scales were unheard of.
And all Weihrauchs had Leather seals fitted back then.
You would need to have followed Gerald Cardews later works in Airgun World to have read his transfer port and stroke experiments.
Most home tuners on here have equipment which Gerald Cardew could only have dreamed about in 1976.
All the best Mick