The 6.23 works very well for super long range precision at low FPS. It all has to do with the air cushion around the bb. In a 6.01 the bb touches the walls of the barrel, stopping the spin from the hopup.
There is a company around who's employees are hitting 350+ feet accurately at 1 joule - 300-350 fps.
However they are running P* fusion engines at max power to get enough air to push the bb at 350 fps, and they are all ER-hopped of I remember right.
The Big Boy - Tanaka M700 AICS - Tan, NC Star 3-9x40E. G&G Fluted Heavy Barrel, Stock inner barrel, G&G hop up unit.
The Backup - TM Five-SeveN - Black. Completely stock.
The Workhorse - G4-A2 Silent Death - Black. STR, ASAP, MOE, SBUS, Pmags, Ranger, RVG, RSA. Super Shooter 14:1, AMP Hi-torque, SHS trigger switch, Deans, Re-wire, BWKK, Eric Built.