RK - I think the factory recommendation is 3/4" - 1" gap between the stone support tray and the lower front ledge.
Re uneven char, I don't think it is the oven. Looking at the photo's closely, it seems that the char follows the cheese outline, meaning the greater the exposure of dough, the more char - that is typical. Uneven sauce or oil may also alter the charring. Maybe I'm missing something.
If it were the rotisserie/stone/oven setup causing uneven charring, it would be the first time I've seen it (and I've been going around and around for years now ). What you might see is a temperature gradient between the center of the stone and the outer rim, but like an old-style grooved record, the temperatures inside the grove should be fairly constant.
If you still suspect the setup, maybe you have one of Chau's pennies (or something else) under the stone, a warped base (rotisserie turned off during warm up), or something causing a air gap in some locations under the stone. I doubt it, but if you want to check, remove the stone and run you hand over the steel tray surface or put a straight edge across various areas of the steel surface and/or the underside of the stone surface. I'm really reaching with these suggestions because I've never seen a stone that has non-uniform bake properties.
Ok, that's fix #1. When I received the oven the tray was laying on the ledge. I had to reset the bushing, and I set the tray about 1/4" above the ledge.
I'll have to be more careful when making my pies. I'm sort of a rustic, lazy type pie maker. I really don't care if I have extra crust on one side, and no crust on the other..I'll have to tighten up my standards.
The temp difference wasn't from the rim to the center. I wanted to see how accurate the temp was at a given point on the stone as it rotated. I chose a spot approximately 2" from the rim, and kept the gun propped up against a chair so it wouldn't move. As the stone rotated, the temp did go from 530-590, 2" from the rim. Maybe a better way to check if it's the tray or the stone is to take the stone out, and measure the temp 2" from the lip of the tray as it rotates. If it's pretty constant, then I would suspect the stone. Maybe the stones density is not consistent.
Warped tray...I do notice a slight deviation in tray movement as it rotates. I wouldn't say it's much, maybe a 1/16" of an inch. I'll look at it a little more.
I believe the only problem with RK's blackened bake was probably just his dough. He said the pizza was a Chicago thin cracker...first reported one on the BS here and it is going to take a little dough tweaking to get a proper cracker off of the BS stone that's all.
What's wrong with Blackened pizza??? I like Blackened steaks and fish.
Other than the suggestions, that I will investigate above, I think CB is right on.
. Practice and patience, and modifying the dough recipe for the BS.
Thanks for the suggestions..