... and on CO2 they run about 710FPS with CP domes, about 16 FPE. I run a crosmods paintball tank adapter and in the fall I switch them to HPA and they go hunting. Haven't chrono'd them with the 1100PSI regulated bottles but I would guess it was higher than CO2.
The other builder was probably "Noodles", he has built several also and posted lots of pix of them around the pool.
Might also search for "rsterne". Bob has wrung about everything possible out of a 2260 and even done big bore conversions.