On Thursday, 13 September 2012 21:13:55 UTC+1, Bob Minchin wrote:
The pressure difference between on and off is too great for consistent
nailing. If the regulator is turned down to below the ON pressure
threshold, this enables constant pressure but this it too low to to
drive anything larger than the smallest of brads (18g) in fully.

What's the tank pressure? It should be high enough to mask this effect.

Is your regulator flowing enough air? Is the delivery hose after the regulator too long and too narrow? The tank pressure should be about 130psi, the regulator about 90 and the pressure at the tool as close to that as possible (my workshop plumbing delivers at 110psi and I have regulators by each bench to avoid this drop).