My HK416 GBB!
Specs:
Iron Airsoft Parts: 416 GBB Conversion Kit & CNC Aluminum Loading Nozzle (BK)
G&P WA Parts: Assemble Parts (Frame Set), M4 CNC Trigger Guard, M4 Type Cocking Handle (CNC Process), M4 Hammer Lock (WP57), Buttstock Speed Buffer & 6.08mm Inner Barrel with Hop Up Chamber
RA-TECH Recoil Spring (Summer Type)
Guarder M4-A1/M16-A2 Steel Flashider (14mm negative)
H&K Parts: HK 416 /AR15 E2 stock, 416/417 Sight Set Complete for Picatinny & HK 416 Battle Grip With Storage Compartment
LMT Parts: 6-position Mil-Spec carbine receiver extension, Heavy CAR Buffer, End Plate & Castle Nut
Actually sold the 553 and put a Aimpoint Pro on. The AP with QRP2 Mount works perfectly with the H&K Iron Sights.
Regards
orb