Specs / O-Rings

O-Ring Sizes

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

Ion / Ion 2.0 / XE and Epiphany use separate o-ring tables below — most sizes happen to match between the two, but don't assume that without checking. Use the table for your specific marker, not the first matching-sounding row you find.

Ion / Ion 2.0 / Ion XE

Concrete sizes for every o-ring you’re likely to replace during service. Sizes are given as AS568 dash number/durometer (e.g. 10/70 means AS568-010, 70 durometer) unless noted as an ID measurement — look up the dash number at any o-ring supplier (McMaster-Carr, The O-Ring Store, etc.) for exact ID/OD/cross-section dimensions. Bring these exact numbers to a paintball shop or o-ring supplier rather than guessing off a worn original — a compressed old o-ring reads smaller than its actual spec size.

Removing old o-rings: a 45° hook pick gives the best angle to get under a seated o-ring and lever it out of its groove without gouging the surface it seals against. If service has lagged, a dried-out o-ring can deteriorate and crumble — in the worst case it comes out in pieces rather than as one ring. Get every fragment out of the groove before installing the replacement; even a small piece left behind will keep the new o-ring from sealing.

Decoding Smart Parts' own part numbers: if you're cross-referencing an original catalog part number, the suffix tells you the material — UR = Polyurethane, BU/BN = Buna-N (Nitrile), HN = HNBR (Hydrogenated Nitrile), VI = Viton (FKM), SI = Silicone, EP = EPDM.

What color should each material be? Useful for checking a rebuild kit — or an o-ring already in your marker — against the Material column above. Confirmed against The O-Ring Store's own current listings (this site's recommended supplier — see Services):

UR (Polyurethane) — clear/translucent.
BU (Buna-N) — black.
HN (HNBR) — sold as either black or green, depending on the supplier's inventory at the time. Both are correct — a green o-ring isn't a sign of a wrong part, it's just how this material sometimes ships.
VI (Viton), if you substitute it for BU per the note further down this page — also typically black.

One limitation worth knowing: black BU and black HN look identical side by side, so color can confirm an o-ring isn't the wrong material (a clear one where BU or HN is specced, for example) but can't always tell BU and HN apart when both happen to be black. A green o-ring, though, is a reliable sign it's HN specifically.

Barrel

Nothing to service beyond the o-ring — see Thread Sizes & Barrel Compatibility for exact o-ring sizes on stock and multi-piece barrel systems.

Feedneck

Location	Size	Material	Part #	Notes
Feed tube friction o-rings (×3)	5×25mm ID	BU	ORN02552070BU	Smart Parts calls this part the "feed tube." Remove one or more if a hopper's feedneck fit is too tight.

Firing assembly / bolt

The bolt itself is identical across Ion 1.0, Ion 2.0, and Ion XE, and its o-ring sizes below apply to all three, per my own hands-on confirmation. The XE’s bolt stop is a physically different part from the 1.0/2.0’s, though — and while its inner o-ring matches, its outer o-ring doesn’t (see the note on that row below). See Rear-Load Bolt for the XE-specific removal procedure.

Location	Size	Material	Part #	Notes
Rear bolt o-ring	10/70	UR	ORN01070UR	On the tail of the bolt, seals against the breech. First check for a leak from the rear of the fire chamber.
Bolt bumper o-ring	15/90	UR	ORN01590UR	Frontmost o-ring on the bolt head. Listed in the Seal Kit table below as "Bolt bumper / ASA seals" — Smart Parts reused the same part for both locations.
Bolt middle o-ring	16×2mm ID	HN	ORN0162070HN	Just behind the bumper o-ring on the bolt head. Check alongside the bolt stop o-rings if the bolt moves forward under pressure without firing. Listed in the Seal Kit table below as "Bolt main seal."
Bolt stop o-rings (×2)	14/70 (inner) and 20/70 (outer)	UR (inner) and BU (outer)	ORN01470UR (inner) and ORN02070BU (outer)	Two different sizes on the same part — don't assume they match. This is the Ion 1.0/2.0/Epiphany size. Ion XE's bolt stop is a different physical part with a different outer o-ring — see the note below the table.
Body breech seal o-ring	20/70	BU	ORN02070BU	Seals the breech itself, separate from the bolt stop o-rings.
Body breech friction o-ring	22/70	BU	ORN02270BU	A different size and location from the body breech seal o-ring above — don't confuse the two when ordering. Same size as the Epiphany's. If BU (Buna-N) isn't in stock wherever you're ordering from, Viton (FKM) in the same dash size is a reasonable substitute — better heat and chemical resistance, at a higher cost, and I've used it myself when BU wasn't available.
Rear breech o-ring	17/70	HN	ORN01770HN	Matches the Epiphany's rear breech o-ring. The Version 2.0 manual's own parts diagram misprints this as 11/70 (ORN01170HN) — the base manual and the Epiphany manual both confirm 17/70 is correct.
SFT o-ring	17/90	UR	ORN01790UR	In the breech, just in front of the barrel. Common cause of paint breaking when worn, especially in cold weather. Also called the "bolt tip seal" in Smart Parts' own Seal Kit documentation below — same o-ring under a different name, a common inconsistency in paintball parts catalogs from this era, before naming conventions across the industry had settled.
Swivel donut o-rings (×2)	15/70	UR	ORN01570UR	Underneath the donut, once the retaining snap ring is removed with snap-ring pliers. Rarely needs service — see Firing Assembly for the removal procedure. Listed in the Seal Kit table below as "Fire chamber seals."

Ion XE's bolt stop o-rings, in detail: the 14/70 (inner) and 20/70 (outer) sizes above are the Ion 1.0/2.0/Epiphany bolt stop, Smart Parts #ION111. The Ion XE uses a physically different bolt stop (#VIB111ASM, confirmed via Tippmann Parts listing it on the Ion XE Addendum, SP1, and Vibe diagrams). Its inner o-ring still matches at 14/70 — expected, since the inner o-ring seals against the bolt shaft itself, and the bolt is identical across the whole family. Its outer o-ring doesn't match, though: per my own hands-on measurement, it takes 18/70 instead of 20/70, since the outer o-ring seals against the bolt stop's own body, which differs between the two parts. Not yet independently confirmed against an official diagram, but treated as correct pending that — so no manual part number exists yet for that 18/70 XE-specific variant.

Ball detents

Location	Size	Material	Part #	Notes
Ball detent bore (×2)	6.35mm diameter	—	—	The hole in the breech each detent (ION108) presses into — measured directly, not a manual-sourced figure. Confirmed identical on an Epiphany body breech. Useful if you're sourcing or designing a replacement detent rather than just replacing the stock part.

Regulator

Location	Size	Material	Part #	Notes
Adjustment endcap o-ring	18/90	UR	ORN01890UR	Around the bottom of the endcap. Check first for a leak from the bottom of the regulator.
Piston o-ring — top	16/70	UR	ORN01670UR	Listed in the Seal Kit table below as "Regulator piston seal, large."
Piston o-ring — bottom	10/70	UR	ORN01070UR	Same number as the rear bolt o-ring, but a different part — don't mix up the two when ordering.
Regulator o-ring	15/90	UR	ORN01590UR	At the top of the regulator body — see the Regulator & ASA page. Same part as the bolt bumper o-ring above. Smart Parts' own manual says a standard CO2 tank o-ring works as a substitute if you're stuck without the exact part.

Solenoid & hoses

Location	Size	Material	Part #	Notes
Solenoid head o-ring	9/70	UR	—	Clear in color. No manual part number found for this one, but my own caliper measurement of the solenoid head post (6.12mm) and the removed o-ring's clear, pliable feel both independently support this size and material — AS568-009's 5.556mm nominal ID stretches onto a 6.12mm post at a normal ~10% (AS568-010's 6.35mm nominal ID would be loose, not gripping, so that size doesn't fit), and "pliable" reads as 70 durometer, not the stiffer 90.
4-mm microline barb seals (×2)	4×1mm ID	BU	ORN0401070BU	Where the 4-mm hoses attach to the solenoid head. Doesn't typically need routine service. Confirmed via my own manual — resolves the two-numbering ambiguity noted below.
Banjo fitting seals (×3)	1.5×3mm ID	BU	—	Black in color. One per banjo fitting (rear, front, and middle). Replacement fittings should already include this seal. No distinct manual part number found for the seal itself, separate from the fitting it comes with.

Sourcing replacement microline: both banjo fittings are standard push-to-connect pneumatic fittings, not a paintball-proprietary format — confirmed by the official manual's own part numbers (ELB1032X18PTCBNJ for the 1/8" line, ELB1032X532PTCBNJ for the 5/32" line). My own OEM tubing samples read Nycoil/Rectus-Tema Polyurethane, 4mm OD × 2.5mm ID, 167 PSI max @ 68°F for the 5/32" line, and 1/8" OD × 1/16" ID (.062") for the 1/8" line, matching my own caliper measurement.

Confirmed source, hands-on verified: TECO Technology sells genuine Freelin-Wade polyurethane tubing at both sizes — part 1J-156-27 for the 5/32" line (.157" OD × .093" ID, 100 ft roll) and 1J-157-10 for the 1/8" line (.125" OD × .063" ID, 50 ft roll). I ordered both, received them, and confirmed the tubing itself is correct spec directly — not just matched by catalog numbers, and no brand-specific order minimum either. Nycoil sells matching-spec tubing (catalog parts 76033 for 5/32", 63220 for 1/8") as a fallback if this listing's ever unavailable — not personally verified, but a real catalog match.

Measured lengths on one Ion, cut to length between banjo fittings: rear banjo (5/32") ≈ 19.75mm, front banjo (5/32") ≈ 103.5mm, middle banjo (1/8") ≈ 49mm. Add a few millimeters of tolerance to each when ordering or cutting — trimming a clean end costs a small amount of length.

Aftermarket bolts: most aftermarket bolts that follow the same overall shape as stock reuse the stock o-ring sizes above. Bolts built from two separate pieces sealed internally to each other — the Firebolt is the common example — use a different internal o-ring not listed here; check that specific product's documentation.

Fasteners

Location	Size	Notes
Grip frame screws (×2, rear)	10-32 × 1"	1/8" hex key.
Grip frame screw (front, under barrel)	10-32 × 1/2"	1/8" hex key.
Grip panel screws	5/16" length, stock	Shorten to 3/16"–1/4" for thin aftermarket grip panels (Hybrid, Dye, Pro-Touch) — stock-length screws can contact and damage the board through a thinner panel.

Most other 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.

OEM service kits

Smart Parts also sold two small-parts kits by official SKU, bundling everything above into a single order rather than sourcing o-rings and screws piece by piece.

Seal Kit — Sku 2668 at release — still available today from at least two retailers under SKU ION051 (“ION/EOS/Ion XE Complete Seal Kit”) — every o-ring (plus the body filter and piston seat) needed for a full rebuild:

Part #	Description
ION120	Body filter
ORN01070UR	Regulator piston seal, small
ORN01470UR	Bolt stop inner seal
ORN01570UR	Fire chamber seals
ORN01590UR	Bolt bumper / ASA seals
ORN0162070HN	Bolt main seal
ORN01670UR	Regulator piston seal, large
ORN01770HN	Bolt guide seal
ORN01790UR	Bolt tip seal
ORN01890UR	Regulator adjuster cap seal
ORN02070UR	Body front/stop seals
ORN02270BU	Outer body seal
ORN02552070BU	Feed tube seals
ORN040170BU	Solenoid barb seals
IRG103	Piston seat
BND001	Rubber band

Part numbers above are as provided in Smart Parts' own official documentation — kept as-is here rather than silently changed, even in the two spots below where an independent source disagrees:

ORN02070UR (Body front/stop seals) — a corrected version of the Ion parts diagram (see Manuals) marks this part as ORN02070BU instead, which matches this page's own Body breech seal and Bolt stop outer o-ring rows above (both Buna-N/BU, not Polyurethane/UR) further up this page.
ORN040170BU (Solenoid barb seals) — that same corrected diagram lists this part as ORN0401070BU instead, one digit longer. Confirmed via my own Ion manual: the longer number, ORN0401070BU, is correct.

Screw Kit — Sku 2674 at release (current availability unconfirmed) — every screw needed for a full rebuild:

Part #	Description
SCRN0440X0188CO	Regulator safety screw
SCRN0448X0250SCO	Trigger adjustment screw
SCRN25028X0500SCO	Trigger bottom adjustment screw
SCRN0632X0313XTS	Grip screws
SCRN1032X0500BS	Bottom line screws
SCRN1032X1000BS	Main frame screws
SCRN1032X0125SCO	Regulator locking screw
SCRN1032X0500VO	Body frame screw
PIN009	Trigger pin

Epiphany

The Epiphany ships stock with a Firebolt, and several sizes below carry the “Firebolt” name accordingly — if you’ve swapped to a different bolt, confirm sizes against that bolt’s own documentation.

Fire chamber / bolt

Location	Size	Part #	Notes
SFT o-ring	17/90	ORN01790UR	Same size and role as on the standard Ion — common cause of paint breaking when worn.
Firebolt bumper	15/90	ORN01590CUR	The Ion 1.0 manual prints this as ORN01590UR — same dash size, durometer, and material (UR). No documentation found for what the extra "C" in the Epiphany manual's version denotes, so treat this as the same physical o-ring in practice.
Firebolt middle o-ring	16×2mm / 70	—	Material not confirmed for this one specifically — the standard Ion's equivalent (Bolt middle o-ring) is HN, but per this site's own rule of not assuming Epiphany parity without checking, that's not carried over here as fact.
Firebolt rear o-ring	10/70	ORN01070UR	Same number as the standard Ion's rear bolt o-ring.
Bolt stop inner o-ring	14/70	ORN01470UR	Matches the standard Ion bolt stop sizing — this is the same physical part (Smart Parts #ION111) across Ion 1.0/2.0/Epiphany.
Bolt stop outer o-ring	20/70	ORN02070BU	Matches the standard Ion bolt stop sizing — same shared part (#ION111) as the inner o-ring above.
Body breech friction o-ring	22/70	ORN02270BU	Matches the standard Ion sizing.
Body breech seal o-ring	20/70	ORN02070BU	Matches the standard Ion sizing.
Rear breech o-ring	17/70	ORN01770HN	Matches the standard Ion sizing.
Swivel donut o-rings (×2)	15/70	ORN01570BU	Same size as the standard Ion, but Buna-N (BU) here — Ion 1.0 uses urethane (UR) — per each manual's own Fig. 18. Part number constructed from the site's own established Smart Parts numbering pattern (dash size + durometer + material code), not independently found written out in either manual. Underneath the donut, once the donut clip is removed — see Firing Assembly for the removal procedure.
Feed tube friction o-rings (×2)	5×25mm ID	ORN02552070BU	Same part as the standard Ion — the Epiphany's feedneck style just uses two of them instead of three, per each manual's own Fig. 18.
Ball detent bore (×2)	6.35mm diameter	—	Matches the standard Ion's bore size — measured directly on an Epiphany body breech, not manual-sourced.

Regulator

Location	Size	Part #	Notes
Reg cover friction o-ring	22/70	—	Epiphany-only, so there's no standard-Ion equivalent to cross-reference for a part number, and material isn't confirmed either. The standard Ion's grip is rubber all the way through, so the rubber itself grips the metal regulator body directly — no o-ring needed. The Epiphany's cover has metal in it (likely a magnesium finish, matching the plated body), which would otherwise sit metal-on-metal against the regulator body — too slippery to stay put on its own. This o-ring sits between them, adding the friction that holds the cover in place and keeps it from rotating freely around the body.
Regulator o-ring	15/90	—	Material not confirmed for this specific row — a standard CO2 bottle o-ring works as a substitute if you're stuck without the exact part.

Higher-pressure hoses and solenoid required. Most Ion low-pressure hoses can already handle Epiphany pressure — check for a rating printed on the hose itself — but the Epiphany-specific solenoid is required regardless; a standard Ion solenoid isn't built to deliver consistent shot-to-shot force at Epiphany pressures. Epiphany-rated solenoids and circuit boards are identifiable by a red protective coil wrap with a black Ion logo.