TBAC SPIRO Suppressor: Redefining Low Back Pressure for Hard-Use 5.56 Gas Guns

Posted by MHSA TEAM on Jan 8th 2026

TBAC SPIRO Suppressor: Redefining Low Back Pressure for Hard-Use 5.56 Gas Guns

TBAC SPIRO Suppressor

Designing a suppressor for modern gas-operated rifles has always been a balancing act. Reduce back pressure too much, and you sacrifice sound suppression. Maximize suppression, and you risk excessive gas blowback, increased cyclic rate, and accelerated wear on the firearm. The TBAC SPIRO was engineered to break that compromise.

Purpose-built for hard-use, full-auto capable 5.56mm carbines, the SPIRO delivers exceptionally low back pressure without giving up meaningful suppression at the muzzle or at the shooter’s ear.

What Makes the SPIRO Different?

The SPIRO is a low-backpressure gas-gun suppressor explicitly designed for rifles like the Mk18 and other short-barreled AR platforms. Unlike many suppressors marketed as “low back pressure,” the SPIRO was developed using an objective, repeatable testing methodology created by TBAC themselves.

Using the TBAC Method of Measuring Back Pressure, SPIRO development focused on four core goals:

  1. Back pressure as low as anything on the market
  2. Muzzle suppression equal to or better than the Dominus
  3. Full-auto capable firing schedule
  4. Less than 6 inches added to overall weapon length.

The result is a suppressor that increases gas flow by only ~50% compared to a bare muzzle—significantly lower than many traditional suppressors—while still delivering substantial suppression numbers both at the muzzle and at the shooter’s ear.

Real-World Performance on Gas Guns

On a 10.5” Mk18-style rifle, the SPIRO increases cyclic rate by only ~5%, compared to ~43% with TBAC’s Dominus-SR. Despite this reduced gas drive, shooter’s ear sound levels remain highly competitive, measuring 136.8 dBA peak with a 124.2 dBA LEq, while muzzle readings remain similarly controlled.

This balance makes the SPIRO especially appealing for shooters who want to run suppressed without adjustable gas blocks, specialized buffers, or tuning every rifle around a suppressor.

Built for Abuse: Material & Durability

The SPIRO is constructed from Haynes 282, a nickel-chromium-cobalt-molybdenum super alloy that exceeds Inconel 718 in both strength and temperature tolerance by roughly 500°F. This material choice allows the SPIRO to withstand extreme firing schedules that would quickly destroy many suppressors labeled “full auto rated.”

TBAC rates the SPIRO in their highest durability class: Hard-Use / Full-Auto MOD 1 (HU/FA/1)

  • Rated for 20+ SOCOM/SURG cycles
  • Tested on an 8” Mk18-style AR, not a 10.5.”
  • Firing schedule includes sustained bursts, rapid semi-auto, and continuous fire.

This testing standard significantly exceeds real-world duty and combat use, ensuring the suppressor’s longevity under extreme conditions.

Mounting Options & Configuration

The SPIRO is offered in two mounting configurations:

  • Direct Thread (1/2-28)
    • Ideal for dedicated gas guns
    • Uses included Nord-Lock washer for retention.
  • HUB / Bravo (1.375x24)
    • Allows user-selected mounting systems
    • Thread-End-to-First-Baffle distance: 1.6”
    • Full-auto capable if the chosen mount remains secure

TBAC notes that future mounting options, including an SR-style interface, are planned.

Accuracy, Expansion, and Use Cases

Despite being optimized for gas guns, the SPIRO maintains TBAC’s reputation for accuracy and repeatability. It is suitable for both carbines and precision rifles chambered in supported calibers.

Current caliber support:

  • .223 / 5.56mm

  • .22 ARC

  • .224 Valkyrie

  • .22 Creedmoor

A dedicated 6mm gas-gun variant is planned for release following SHOT Show 2026.

Minimum barrel lengths range from 8 inches for 5.56 up to 18 inches for .22 Creedmoor, making the SPIRO a versatile suppressor across duty, training, and competition platforms.

Why the Name “SPIRO”?

“Spiro” comes from Latin, meaning “to breathe.” Pronounced “SPEAR-oh,” the name reflects the suppressor’s core purpose: allowing a gas gun to breathe more naturally while suppressed, reducing blowback and stress without sacrificing performance.

Final Thoughts

The TBAC SPIRO is not just another low back pressure suppressor—it’s a deliberately engineered solution backed by transparent testing, extreme durability standards, and real performance data. For shooters running short-barreled 5.56 gas guns hard and often, the SPIRO offers a rare combination of reliability, suppression, and shooter comfort.