Reference / O-Rings

O-Ring Sizes

Already know your marker and just need the numbers? This is the same spec data as the Ion 1.0 guide's specs page — kept here as a fast lookup with no rebuild-guide framing around it.

Concrete sizes for the o-rings you’re most likely to replace during routine bolt/firing-assembly service. Sizes are given as width/durometer (e.g. 10/70 means 1/10” width, 70 durometer) — bring these exact numbers to a paintball shop or o-ring supplier rather than guessing off a worn original, since a compressed old o-ring reads smaller than its actual spec size.

Location	Size	Notes
Rear bolt o-ring	10/70	Seals against the breech. First place to check for a leak at the rear of the fire chamber.
SFT o-ring	17/90	Inside the breech, just in front of the barrel — seals against the bolt during firing. Common cause of paint breaking in cold weather when worn.
Swivel donut o-rings (×2)	15/70	Underneath the donut, once the c-clip is removed. Rarely needs service — check only if you're chasing a leak specifically at the donut.

These sizes apply to the stock bolt/breech configuration. Aftermarket bolts that follow the same overall shape as stock typically reuse the same o-ring sizes — bolts with a different internal sealing approach (integrated internal o-rings rather than the stock arrangement) can differ. Check the specific aftermarket part's documentation if you've swapped bolts.

Torque specs

Most fasteners on the Ion are low-torque, hand-tight-plus-a-quarter-turn fittings rather than precision torque-spec hardware — overtightening is a far more common failure than undertightening. Specific numeric torque values will be added here as they’re confirmed through hands-on testing rather than estimated.