Comstock Armory Extended Steel HPA - Plan-B Compatible Adapter

Comstock Armory Extended Steel HPA - Plan-B Compatible Adapter

Engineered for maximum compatibility and minimal weight, this Extended (XL) Plan-B HUB suppressor adapter is designed to work with Comstock, Rearden, and other common Plan-B pattern muzzle devices. At just 1.9 ounces, it is currently one of the lightest extended steel Plan-B HUB adapters available.

Compared to standard low-profile adapters, this model provides an additional 0.4" of blast chamber space, allowing clearance for longer muzzle devices while maintaining a streamlined footprint. The 1.08" rear cylindrical section is designed to tuck under most handguards for a clean, integrated look.

Precision machined from 17-4 PH stainless steel and finished in durable black nitride, this adapter offers strength, corrosion resistance, and long-term durability in demanding conditions.

Extended / XL Configuration
Adds 0.4" of blast chamber space for longer muzzle devices.

Plan-B Pattern Compatible
Works with Comstock, Rearden, and similar Plan-B muzzle devices.

HUB / Bravo Threads (1.375-24)
Compatible with most modern rifle suppressors.

17-4 PH Stainless Steel
High-strength construction for hard use.

Black Nitride Finish
Enhanced corrosion and wear resistance.

Low-Profile Rear Section (1.08")
Fits under most handguards.

Tooling Interfaces
Features 1-7/16" wrench flats and 1.5" spanner notches.

Ultra-Lightweight
Only 1.9 ounces.

Specifications

• Thread Pattern (Suppressor Side): 1.375-24 (HUB / Bravo)
• Material: 17-4 PH Stainless Steel
• Finish: Black Nitride
• Weight: 1.9 oz
• Added Length: 0.7"
• Rear Diameter: 1.08"
• Compatibility: Plan-B pattern muzzle devices