Andrea at GINB has asked me to buy an HW100 cylinder with "the new quick fill system" and send it over to them for an HW100 bullpup project (to resemble a P90 assault rifle!). Could someone explain what the "new" one looks like, whether it comes in different lengths, and where's the cheapest place to buy one please? If there isn't one brand new to the market recently, then he must mean the latest version. Any help appreciated as I'm not up to speed with HW100s. If anyone has such a cylinder to sell 2nd hand I'd be interested too.