Everything between the cylinder and the rifle. Most of what goes wrong when charging a PCP is a fitting problem, not a rifle problem, so it is worth getting this end right.
The probe must match the rifle. Fill probes are not universal — an HW100 probe will not fit a BSA, and a generic probe is only generic within the pattern it copies. Check your rifle's fill port before ordering. Best Fittings make the bulk of what is here, including dedicated HW100 and BSA probe kits alongside the generic pattern.
Threads. The common sizes are 1/8in and 1/4in BSP, with double-male couplings to bridge the two. If you are building a set-up from scratch, the quick-coupler starter kit saves buying plugs and sockets piecemeal.
Hoses. Microbore hose in 600mm holds far less air than a wide bore, which means less to bleed off and a gentler fill. Bisley's 300 bar hydraulic hose covers cylinder-to-pump work.
O-rings are consumables. A slow leak at the probe is nearly always a perished O-ring, not a faulty rifle. Keep spares — they cost pennies and they always fail on a shooting day.
Two safety points worth stating. Fill to the rifle's rated working pressure and no further; more is not better and the manufacturer's figure is the figure. And a diving cylinder needs an in-date hydrostatic test certificate before a filling station will touch it — check the stamp on the neck before you drive anywhere.
In Scotland an Air Weapon Certificate is required to buy, use or possess an air weapon. The cylinders, hoses and fittings on this page are not air weapons and are not certificated; the rifle they charge is. See Air Guns and Airgun Accessories.
