Remember that a barrel past 450mm doesn't really increase accuracy. You may get a few more fps if you match the cylinder correctly and have good compression though. If I were you, I would just get a VSR10 platform, unless you really like the looks of the M24.Waking up early I had time to do more research, and from what I have read the APS-2 System is a lot better because it can move more air faster, and have a longer barrel (About 700 mm). In the same thread they said there aren't as many DIY Mod's for the APS-2 System (Which would be a downside because most can be achieved with little money, but with time which I have). This particular person was stating that the hop up tends to adjust itself over time too? Is this true?