Cylinder to Inner Barrel
 

I just picked up a G&G F2000 (g2010) and it comes with i believe a 450ish length inner barrel. It also has a ported cylinder (1 port towards the end - Type 1??)

I have a nice 500 mm tight bore that i want to put in this but not sure if the cylinder will support a barrel of this length?

You will want an unported cylinder