Kakasi Tactical built a Geissele MK4 FBI HRT GBB Rifle that has the VFC M4A1 2015 DX version. It should help put a good impression of the FBI HRT which we actually dig their loadout. If you want the list of parts and accessories he used, here they are:

• Geissele mk4 Federal OD
• Magpul CTR stock OD
• Magpul MOE+ pistol grip OD
• Noveske 60 Degree Ambidextrous Safety Selector
• Crusader steel BCG with Aero marking
• 3D print geissele straight type trigger
• Original made Cerakote lower reciver with Aero marking