Airsoft Outlet NW have been taking a look at modifying AEGs with new inner barrels:
With the plethora of airsoft upgrade parts available, a lot of new (or experienced) AEG owners feel the drive to customize and upgrade their guns. Sometimes this even means modding new, unfired AEGs to work ‘better’. One of the most common modifications is a new inner barrel. Especially in some brands, this is actually a very good idea. Before you go extending the barrel and using a mock suppressor, you’ll want to understand how your barrel length plays with your cylinder size and spring rate.
Depending on which AEGs you’ve worked on, you may have seen non-ported cylinders, cylinders with a rearward port, or cylinders with a port that’s fairly far forward. These different cylinders are made for use with varying lengths of AEG barrels.
http://www.airsoftoutletnw.com/news/matching-aeg-cylinders-to-inner-barrels
