The Mountain Billy Gun Goat-15 Helium is an AR-pattern rifle chambered in .22 LR with a 16-inch threaded barrel. It has a black finish and ships with a 10-round magazine. 
 

Key Specifications 

• Brand: Mountain Billy Gun 
• Model: Goat-15 Helium 
• Caliber: .22 LR 
• Action: Semi Auto 
• Barrel Length: 16" 
• Capacity: 10 
• Color/Finish: Black 
   

Detailed Features 

• 16-inch threaded barrel 
• AR-pattern controls and layout in .22 LR 
• Black finish throughout 
• 10-round magazine 
• Threaded muzzle for device compatibility

Owners of the Goat-15 Helium appreciate the .22 LR chambering in a familiar AR-pattern layout, which makes it well-suited for lower-cost range sessions and training without switching platforms. The threaded barrel gets positive mentions from those looking to add a suppressor.

As a smaller brand, Mountain Billy Gun draws some skepticism about long-term parts availability and customer service compared to established .22 LR AR makers. First-time owners generally report the rifle cycles reliably with quality .22 LR ammunition, though some note sensitivity to bulk or low-velocity loads.

The 10-round capacity is occasionally mentioned as a limitation, particularly for users expecting higher-capacity options common in other .22 LR semi-autos. That said, for its niche as a lightweight trainer, the Goat-15 Helium earns reasonable marks.