I am wondering what is the average casting distance that custom rod builders are getting out of thier spinning rod set ups.

I just built a 7ft CRB 8-10# light action rod.
I have a 21 inch reduction train and 5.5mm running guides. I tested it this afternoon and with a 2500 shamino reel with 10# mono.
with a 1/2oz spilt shot, I was getting an average distnace of 93ft with out loading the rod to much, on a full load i was getting 152ft average. I used my speed meauring laser for my readings.
I was getting no line slap and the line seemed to be tamed after passing the choker guide.
the guides i used for my reduction train is a 30-18-10-6 these were guides i had laying around and wanted to see what i could do with them.

I think you're probably in the ball park. I was going to say that a rod in that range should comfortably average about 115 to 125 feet without undue effort.

.............

Just curious what is that device you used for the measurements. Can you provide a bit more details?

I used my laser that I use at work. It gives speed and distance and is checked every 6 months. I placed a mark on the road as a start point and sent my wife out to mark where the weight landed. I painted the weight neon orange to make it easier to see and it leaves marks on the roadway when it hits. I did three cast and did and average.

Just trying to imagine the response if I asked my wife to run out and measure my casting distance.... You are a lucky guy Jason...