Cronies will read the FPS even if it shoots 3 or 6 BBs at a time?

^^ I'm curious too; how does one chrony a multi-barrelled gun? I've wondered how hard my goblin deuces (technically barrel-less, unless the shell's 4 feed tubes count) shoot on CO2... Couldn't think of an accurate way to test 'em.

Maybe just fill one bb into the shell?

Negative. Your fps would report significantly higher since the same amount of gas that normally would shoot 3 it 6 BB's would only pushing out 1 BB.

divide that number by 3 or 6 then? since I assume each chamber would be getting the same amount of gas...

You know my facebook info... thus... you know how to get one. But they are NOT for sale here, let's get that much straight.

We chronied them in the shop using i think it's a mad bull. Rectancle with a big hole off to the left side.

You'd hafta plug the other barrels up airtight, and I wouldn't be sure of the maths. It gets tricky when each feed tube in the shell holds multiple BBs (the deuce holds 3 per, for a total of 12 BBs per shell, fired at once; 24 if both barrels are fired).