Specs / Threads

Thread Sizes & Barrel Compatibility

Barrel thread

The Ion family uses what's now called the Ion thread — originally named the Impulse thread, and renamed once the Ion's popularity overtook the Impulse's. Spec is 15/16"-12. Sometimes still referred to as the "Smart Parts Standard" thread.

Barrels threaded for any of the following will fit an Ion, Ion 2.0, Ion XE, or Epiphany interchangeably: Impulse, Impulse 08, Nerve, Luxe, Shocker NXT, EOS, SP-1, SP-8, Vibe.

Component	Size	Notes
Barrel front o-ring	19/70	Seals barrel front to barrel back on multi-piece barrel systems.
Freak back insert o-rings (×2)	18/70	Hold the Freak insert in place internally.
Stock barrel o-ring	18/70	Factory-installed on Impulse/Ion/NXT/Luxe one-piece barrels.

Feedneck thread

A separate spec from the barrel thread above — don't assume a feedneck and a barrel from the same-sounding source both fit. Ion 1.0, Ion 2.0, and Epiphany all use the Ion/Shocker SFT feedneck thread (also shared with Impulse and Nerve), but the XE switched to the Ion XE/Shocker NXT feedneck thread — a feedneck that fits one won't necessarily fit the other, even though the barrel thread is identical across all of them.

The 2.0's stock feedneck is a different physical part from the 1.0's — it matches the Epiphany's — but it's still on the same Ion/Shocker SFT thread family.

Fastener & fitting threads

Component	Thread	Notes
Grip frame screws (all three)	10-32	1/8" hex key. Thread is universal, but Epiphany screws are physically shorter than Ion's — see warning below.
Banjo / microline fittings	10-32	Push-to-connect style, 1/8" hex key for install/removal.
QEV (quick exhaust valve)	10-32	Most standard 10-32 QEVs fit, though the SP 360 QEV is purpose-built for the Ion and installs/removes the same way as the stock middle banjo.

Don't cross grip screws between Ion and Epiphany. The thread is the same 10-32 on both, but Epiphany screws are shorter — using Ion-length screws on an Epiphany can damage the circuit board through a thinner grip panel. Keep the two sets separate if you're working on both.

Regulator internals are reverse-threaded — this isn't a size spec, but it trips people up as much as one. See Regulator & ASA before disassembling one expecting standard threading.