The Springfield Armory Hellion is a bullpup semi-automatic rifle chambered in 5.56x45mm NATO with an 18-inch barrel, gas piston operating system, and black finish. Capacity is 30 rounds. Weight is 8.2 lbs. 
 

Key Specifications 

• Caliber: 5.56x45mm NATO 
• Action: Gas Piston, Semi-Automatic 
• Capacity: 30 Rounds 
• Barrel Length: 18 inches 
• Weight: 8.2 lbs. 
• Sights: Flip-Up Front & Rear (Elevation and Windage Adjustable) 
• Optic Mount: 1913 Picatinny Rail 
• Muzzle Type: Flash Hider (four-prong) 
• Finish Color: Black 
   

Detailed Features 

• Short-stroke gas piston, two-position adjustable 
• Five-position adjustable stock with cheek riser 
• Flip-up sights, elevation-adjustable front and windage-adjustable rear 
• Four-prong flash hider 
• 1913 Picatinny optic rail 
   
  The 18-inch barrel is the mid-length option in the Hellion lineup, splitting the difference between the 16-inch and 20-inch variants. The four-prong flash hider is specific to this variant. The two-position gas block accommodates suppressed use.

The Springfield Hellion with the adjustable gas system in 5.56 NATO draws the usual range of Hellion feedback, with the 18-inch barrel and four-prong flash hider occasionally noted as distinguishing details.

Reliability with standard 5.56 NATO brass is consistently positive across user reports. The adjustable gas system is mentioned as a practical feature for those running suppressors. Accuracy reports are solid for the platform.

Trigger pull is the most common point of criticism. The bullpup linkage produces a heavier pull than most users want, and experienced shooters coming from direct-mounted triggers tend to notice it most. Weight at 8.2 lbs is on the higher end for a 5.56 NATO semi-auto, which comes up in discussions about field carry.

The aesthetics of the black finish are well-received. Price, as with other Hellion variants, sits at the higher end for the bullpup segment. Users frequently compare it against the Tavor X95.