[Zack The Ripper]

So I have a question regarding barrel length in relation to cylinders. As the title suggests I have a G&G SCAR. I'm adding a tight bore barrel which is longer than the 300mm stock barrel as I have a suppressor/barrel extension. Now I have been told by some people that it can get tricky when going anywhere beyond 400mm in length as if your cylinder isn't big enough, you won't have enough compression space for the length of the barrel. I heard some talk saying you need a "full cylinder". Now I know some stuff about internals, enough to get by, but this is an area I'm clearly clueless on.

I have a 380mm TBB I ordered, but I have to option of changing that to a 407mm if I want, and I kinda want to. I'm just wondering what effects this may have as I'm not sure what kind of cylinder I have in my SCAR, nor do I have any idea if there was any fuckery in what I had heard regarding cylinder size. Basically I'm just trying to find out if the 407mm length TBB is a good choice for the SCAR.

Any info is appreciated.

Thanks!

Zack