I use a AT85 marker made by Advanced Tactical Systems (ATS). It's a select fire (semi/full auto) chain fed that is very unique in the paint ball industry. My AT85 has been modifed to resemble a M4 or CAR-15 assault rifle while still retaining the forward loader. Parts used: I purchased the CAR-15 stock from funsupply for $85 AR-15 A2 removable carry handle sights from Cheaper Than Dirt for $70 ATS I got a flat top rail adapter for $10, a front sight for about $40 bucks and a strait ASA conversion for $50. Assembly: Clean and dry the area around the sight rail. Attach the flat top using super glue, used locktite super glue. Apply the glue to the bottom of the new flat top rail. Then place firmly on the top of the gun. You need to apply firm pressure while the glue dries. I used gaffers tape to hold it on. Attach the front site by cutting thin long strips of Gaffers tape that are the same width as the two attach points on the fron site. Wrap the tape just on either side of the from vent holes. keep wrapping the tape until the sight slides on firm. then tighten with the tension screw on the bottom of the sight. Images: