There is no correlation between trigger pull and the hammer impact force. IF the sear and the full-cock notch have a nice tuned fit. The force on hammer fall comes from the MAINSPRING strength and the weight of the hammer. Now, you probably don't want to change out to a different weight hammer. So you will be concerned with the force applied by MAINSPRING. A stronger mainspring, and you get more hammer strike force. Not linear and exact relationship, but that's the way it works. Why does the trigger pull force have nothing to do? Because the sear notch on the hammer is in the same place REGARDLESS of how much force you set the trigger up with. Since the hammer fall starts in the same place (when sear clears the full cock notch), and the mainspring works on the hammer through the same amount of rotation, all that matters is how strong that mainspring is (and how smooth the hammer pin and side walls of the hammer slot in the frame are, to eliminate any friction). A heavy spring on the trigger or sear only adds to the force you have to apply to the trigger. The trigger does not transfer any of the trigger pull force to the hammer.
You use the chrono and lower the powder charge (MAYBE 1 GRAIN STEPS) until you get your desired velocity. Once there, you fire 25 or 50 rounds in practice sessions to make sure you get a working discharge of both shot and wad EVERY TIME. Using a double barrel, load two rounds, fire them, then look from the chambers down the barrel to make sure everything cleared the barrel. Pump gun testing would be harder to do (use a cleaning rod to punch out the barrel) and tell you nothing extra about the function of the shells.
If you start getting sunken crimps due to the lower charge weights, you may have to find a taller wad or put less pressure on wad seating or lower the level of the crimp die settings. Or use a more bulky powder. Clays was a great powder for light shotshells for cowboy shooting. Titewad and Titegroup are less satisfying because they are not as bulky and can give you fits with the "stack height" that supports the crimp petals and prevents sunken (leaky) crimps.
good luck, GJ