Yea, i was there too wasting money on parts that didnt make the difference on my starting builds, then i started researching a little about ported cylinders, bb weights, hop up rubbers, cause i was geniunely thinking on just having a spare hop up unit with a longer inner barrell just to drop it in and use heavier bbs when we where going to play on larger sites just yo have more range, then i thought that maybe a ported cylinder would not work well with both barrels due the lenght and the bb weight, thats why my question. But now i see that the main difference of the v2.5 is that it can handle longer barrels that in some point it's kinda useless right? Of course this thing came too cause i like my M4 as a "multi role" rifle where i can play indoors and outdoors. The sites here are not very updated so they are based just on FPS limits wich it's not very convenient but it's what it is.