The steel targets, especially the poppers, are supposed to be "set" to fall from a low hit with 115 grain 9mm from a G26 (if I recall the rules correctly). At the last Richmond, CA match, they weren't always so set, so the SOs used "ring and paint" to call a hit. This is also approved for use in windy conditions.
I was at the Norco match this past weekend with my G19 and G34. I hit one of the pepperpoppers a little low in the middle of the popper, but it didn't go down (I have a friend as a witness). I had to take a second shot at the top of the popper.
Otherwise, a 9mm shouldn't be a problem. Just shoot for the top of the poppers.