Modding bb gun

[battlemonkey]

I still have not got around to making my bbmg after many weeks. first it was trying to find 6mm aluminium tubing, then it was finding I couldn't get it and now i've just got a MT125R race bike that goes 115mph so thats taken up time stripping it down and making it look nice.
Now i have some spare time i want to make my kick ass vortex. i thought about taking out the middle of a cheep bb gun and replacing it with tubing but i don't know what the smallest size tubling u could use for a bbmg was. could someone tell me

This is the racer. It's a MT125R with a mugen kit on it.
[img]<a%20href="http://img80.imageshack.us/my.php?image ... ck.us"></a>[/img]

[blind909]

what, are you talking about th chamber size, if you are, i have used 1/2".

[HaiThar]

wait so what's the bike for? I didn't understand...

[battlemonkey]

yes blind909 i was looking for the minimum size i could use on the chamber. was just showing pic of bike cause i like it