Air
Home to the world's quietest airgun moderators, plus precision pellet caddies, self-healing targets, chassis parts, and shooting accessories, all designed and manufactured by Silent Thunder Ordnance. From the Accipiter and Sarissa lines to the Pocket Benchrest and Eyeshine Targets, this is the full catalog of STO air products built for performance and tested before they ship.
Pugio
Pugio
The Pugio is our compact moderator, carrying a dimensional envelope of 40x100mm and a weight of 82 grams. It exists for one reason: when size and weight matter more than maximum sound attenuation. That's a real tradeoff, and it's worth being direct about. The Pugio will meaningfully reduce your rifle's sound signature, but it will not match the performance of a Falx or Sarissa. If you can fit a larger moderator on your rifle, you will get better results with one. The Pugio is for situations where you genuinely can't.
The design uses Nikola Tesla's Gas Diode to reflex propellant air back on itself, resisting forward flow through geometry alone with no moving parts. This three-stage approach first strips air off the pellet to reduce turbulence and improve accuracy, then delays it through compound gas diode stages, and finally passes it through a high-performance damping section to absorb residual sound energy. Critically, the design adapts along its length rather than repeating a single approach end to end, applying the right technique at the right point in the air's journey through the moderator.
Unlike our larger moderators, the Pugio does not offer separate flow-tuned variants. The space constraints mean all configurations have a high airflow-to-diode ratio regardless of host, so the diodes have been redesigned specifically for maximum airflow control within that constraint. The result is a single core that performs well across Standard and Moderate flow rifles. At High flow conditions the Pugio continues to reduce sound meaningfully, but the rifle will remain loud and we recommend aluminum end caps for high power shrouded and moderate power unshrouded rifles.
Key Features:
Tesla Gas Diode design: Compound diode stages reflex and delay propellant air through geometry alone, no moving parts
Adaptive staged architecture: Design transitions along its length to maximize attenuation at each point in the air's travel
Tapered bore: Improves sound attenuation while reducing the likelihood of pellet clipping
Single universal core: Redesigned diode geometry optimized for maximum airflow control within a compact envelope
End cap options: Delrin caps for minimum weight; aluminum caps recommended for high power shrouded and moderate power unshrouded rifles
Built and tested in the USA
Select your thread and end cap configuration using the dropdowns below. Information on calculating your rifle's flow factor can be found in our Moderator Configuration & Optimization guide.
This product is intended for airgun use only. Use of this product in any manner inconsistent with its design intent is a violation of federal law. More information about the federal court ruling which clarified the legality of airgun moderators in the United States can be found here. Local restrictions may still apply. It is the responsibility of the buyer to ensure compliance with all applicable laws.
This item ships within the United States only.
Flow Factor Reference
The Pugio doesn't have separate flow-tuned variants, but flow factor still determines how well it will perform on your rifle. Our Moderator Configuration & Optimization guide walks through how to calculate your flow factor. The reference hosts below give you a sense of where your rifle sits:
Standard Flow: Tuned on an FX Crown .22, 32 ft-lbs. Factory config w/ extended shroud, acoustic peak 288.0. Flow factor 460.
Moderate Flow: Tuned on an FX Crown .30, 80 ft-lbs. Factory config w/ extended shroud, acoustic peak 637.6. Flow factor 1,111.
High Flow: Tuned on an FX Dreamline .30, 87 ft-lbs. Bare muzzle, acoustic peak 3,668.4. Flow factor 6,500.
Extra High Flow: Tuned on an AEA Challenger .35, 150 ft-lbs. Bare muzzle, acoustic peak 5,255. Flow factor 16,333.
The Pugio performs well at Standard and Moderate flow. At High flow it will still reduce your sound signature meaningfully, but if your rifle falls into that range and maximum attenuation is the priority, a Falx or Sarissa will serve you better.
Sound Profile Data
A note on reading these traces: peak alone doesn't tell the full story. Post-peak sound character has a substantial effect on perceived loudness, often more than the peak value itself. Each trace is provided so you can evaluate the full sound profile rather than a single number. Note that traces are not shown to the same scale.
Pugio Rev.3, as tested on a shrouded FX Crown .30. Average peak 199.73.
Rev.3 represents a complete re-engineering of our damping system, combining the diode advances of previous versions into a more integrated structure while dramatically increasing closed damping material surface area and more precisely tuning open damping material flow resistivity and impedance. At moderate flow the Pugio delivers a meaningful reduction in peak sound for its size, though post-peak sound reflects the space constraints inherent to a moderator this compact. Additional traces across other host configurations will be added as testing expands.
