Tippman is slated to release a dual gas system M4 in the next couple of months. Apparent price point will be around $400, and mags $25. It comes with an adjustment valve inside, and can run on HFP and CO2, both of which are more consistant and stable than propane/green gas.
There are several threads from people asking this exact same set of questions. Also several reviews, upgrade threads, etc. Use the search function to access this information, so that we aren't posting it over and over. Then you can ask the educated questions that are not posted up yet. Aper is correct, and it is a forum stand-point, to make people research and familiarize themselves with ASC before asking "can everyone else do the work for me?".
ďREALITY IS LIKE A STONE. TO MANY ITíS HARD AND COLD, THEY CANíT HUG IT OR EAT IT, IT ONLY FRUSTERATES THEM AND DOESNíT DO THEM MUCH GOOD. TO OTHERS ITíS STRONG AND DEPENDABLE, YOU CAN BUILD WITH IT, BUILD UPON IT, OR WORK WITH IT, ALSO USE IT TO SMASH PEOPLE IN THE FACE.Ē