Last reviewed: 2026-04-17 by Jake Terry, FFL07/SOT3, with hands-on install experience on AR/AK/Glock platforms.
The Geissele Super MPX SSA trigger is a two-stage assembly purpose-built for the SIG SAUER MPX pistol-caliber platform. This trigger adapts Geissele’s CRANE-certified Super Semi-Automatic (SSA) design — originally engineered for M4 carbines — to the MPX’s unique bolt geometry and recoil profile. Total pull weight is 4.5 lbs, split across a smooth 2.75-3 lb first stage and a clean 1.5-1.75 lb second-stage break. The trigger body is machined from S7 tool steel and finished in Geissele’s Nanoweapon coating to resist wear under the MPX’s direct blowback cycling.
How It Works
The Super MPX SSA uses a wire hammer spring and a conventional disconnector geometry, but adds a tailored recoil spring system. Geissele provides three custom buffer springs — yellow, red, and white — that adjust the MPX’s bolt carrier recoil impulse based on ammunition power factor. Start with the yellow spring for 115-124 gr 9mm loads, observing ejection angle and bolt lock function. If the bolt rides too far rearward or the ejection pattern is erratic, step up to the red or white spring. This tunability extends the service life of the trigger components, bolt carrier, and lower receiver by moderating impact forces. The Nanoweapon coating — applied to all trigger surfaces — provides 69 RC hardness and a 1-2 micron film thickness, matching the corrosion resistance of hard chrome without dimensional buildup.
Specs at a Glance
| Spec | Value |
|---|---|
| Type | Two-stage, non-adjustable |
| Platform | SIG SAUER MPX (not compatible with AR15/M4 PCC lowers) |
| Pull weight | 4.5 lbs total (2.75-3 lb first stage, 1.5-1.75 lb second stage) |
| Material | S7 tool steel |
| Finish | Nanoweapon coating (69 RC, 1-2 µm) |
| Shoe | M4 curved |
| Drop-in | Yes, includes three custom recoil springs (yellow, red, white) |
| Manufacturer | Geissele Automatics |
The Super MPX SSA fits only the SIG MPX lower receiver. AR15-pattern pistol-caliber carbine lowers use different fire-control pocket dimensions and will not accept this trigger group. For the complete Geissele trigger line — including AR15, AR10, and AK variants — see our full catalog.
Safe Handling & Compliance
Per current ATF guidance, this trigger is classified as a semi-automatic trigger assembly — each round fired requires a discrete trigger function, and the device does not convert a firearm to automatic fire. Regulatory status has changed before and may change again; verify current federal and state law before ordering.
- Follow the four rules of firearms safety during installation and live-fire testing.
- Some states restrict aftermarket triggers or require gunsmith installation — consult your local statutes before ordering.
- After installation, perform a function check: with the firearm unloaded and pointed in a safe direction, cycle the charging handle and confirm the hammer follows the bolt carrier without releasing. Apply the safety and pull the trigger; the hammer should not fall. Disengage the safety and pull the trigger; the hammer should fall cleanly. If any malfunction occurs, cease use and consult a qualified armorer.
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