Fully upgraded arp556 for sale. 18:1gears, 8mm ball bearings, maxx nonported cylinder, maxx double oring cylinder head, maxx double oring piston head, double oring tappet plate nozzle. Flat hop bucking and nub with a gate titan mosfet so you can fully program the gun to your liking. Comes with a red dot sight, sight protector and an ace tech tracer/crono unit. Great gun for indoor. Located in Calgary