July 17th 2017 FX Royale air rifle regulator air leak fix, regulator adjustment, barrel removal. LOOK BELOW FOR REG ADJUSTMENT TIPS AND O-RING SIZES! General tips to assemble this air gun. Maintenance tips for this and other pellet guns. Can also be applied to the 400, 500, and Boss air rifle. I also cover how to clear a pellet from the barrel, change the breech O-ring, and fix a leaking fill probe. This is a quote from an exceptionally helpful member on Airgun Nation.... "the brass nozzle will change regulator pressure if you turn it. The brass plunger with the belleville washers holds the delrin seal, and moves back and forth to regulate the pressure. The brass regulator nose has got a conical shape to form a sealing surface in correlation with the delrin seal of the plunger. If you back out the regulator nose, the piston has to travel a longer way to form a seal against the reg. nose, hence the belleville are also compressed more, creating more resistance. (=higher reg. pressure) In fact, increasing spring tension to increase the reg. pressure is about the same as backing out the reg nose, with the difference that in the last case the plunger has gotten a longer stroke. More travel equals more spring tension. Audrius and huma regulators work according this principle, the pressure is controlled by moving the reg. nose in or out, instead of increasing spring pre-tension. Turn in is less pressure, turn out is more pressure. Long story short, the reg. nose should be hand tight, to just let it sit against the ridge in the reg. body. The o-ring will provide the seal. Hold reg. body with a loose grip between your fingers to tighten, when it starts to slip through your fingers, it is tight enough." O-ring sizes: 2.9X1.78 (1x) 6.07X1.78 (1x) 7.66X1.78 (1x) 11.6X2.4 (2x) - These are the two main ones on the outside.