Comstock Armory .300/.308 Quick Detach Recessed Plan-B HUB Suppressor Mounting Kit The Comstock Armory .300/.308 Quick Detach Recessed Plan-B HUB Suppressor Mounting Kit combines two .30-caliber recessed micro muzzle brakes with one steel RPA HUB adapter. Both brakes use 5/8x24 threads, giving two compatible .30-caliber firearms a shared Plan-B mounting interface for one compatible suppressor. This package keeps the hardware focused on a compact, recessed configuration. This kit contains everything you need in mounting hardware to mount your compatible HUB suppressor to multiple 5/8x24-threaded .30-caliber firearms while keeping an ultra-tight, low-profile mounting system. Two included brakes support two compatible .300/.308 applications within the suppressor's cartridge rating. Shop this Comstock Armory .30 Cal mounting kit at BattleHawk Armory for a compact Plan-B setup across two compatible firearms. Kit Contains 2x Comstock Armory Recessed Micro Plan-B Muzzle Brake, 5/8x24, .30 Cal, Black Nitride - SKU: MBM-58-30-R - UPC: 850069580315 1x Comstock Armory RPA HUB Recessed Plan-B Suppressor Adapter, Stainless Steel - SKU: RPA-B-SS - UPC: 850069580285 The package contains three mounting components: two muzzle brakes and one suppressor adapter. Firearms and a suppressor are not included. Recessed Plan-B HUB Mounting The RPA-B-SS adapter connects a compatible 1.375-24 HUB/Bravo suppressor to the included Plan-B-pattern muzzle devices. Its recessed profile positions the muzzle device 0.40 inch deeper than the standard Comstock LPA, shortening the assembled mounting configuration and helping create a tighter handguard-to-suppressor gap. The adapter itself adds 0.18 inch of length and weighs 2.1 ounces. One adapter serves the compatible suppressor while the two brakes provide matching attachment points on two firearms. Quick-detach convenience and the recessed profile work together for a compact system. Actual spacing depends on the firearm, muzzle device and suppressor combination. Matched 5/8x24 Brakes for .30-Caliber Applications The two MBM-58-30-R brakes accept projectiles up to .308/7.62mm and use 5/8x24 barrel threads. Each measures 1.25 inches overall, adds 0.42 inch beyond the muzzle and weighs 1.2 ounces. Matching muzzle devices let two compatible .30-caliber firearms use the same suppressor-side adapter while retaining the short recessed micro profile. The recessed micro brake design reduces recoil and acts as a sacrificial surface ahead of the suppressor blast baffle. Its rotationally symmetric geometry does not require timing with shims. Limited forward protrusion is useful with the recessed adapter, while the complete combination still requires adequate internal clearance. 17-4 PH Stainless Steel and Black Nitride Both muzzle brakes and the RPA adapter use 17-4 PH stainless steel with a black nitride finish. The kit pairs professional-grade steel components with a consistent black appearance. The included adapter is the steel RPA-B-SS configuration, with the same material and finish family as the recessed micro brakes. Compatibility and Clearance Both firearms must have compatible 5/8x24 muzzle threads and a barrel diameter of 0.750 inch or less where the recessed brake overlaps the barrel. The brakes are limited to projectiles up to .308/7.62mm. The suppressor must have a compatible 1.375-24 HUB/Bravo rear interface and be rated for the exact cartridge and barrel length. Confirm blast-chamber and handguard clearance for both configurations. Product Specifications Component manufacturer: Comstock Armory Configuration: .300/.308 Recessed Plan-B HUB Mounting Kit Included hardware: Two recessed micro muzzle brakes and one steel RPA adapter Barrel threads: 5/8x24 on both muzzle brakes Caliber / bore limits: .30-caliber applications; bullets up to .308 / 7.62mm Suppressor rear interface: 1.375-24 HUB/Bravo Muzzle-device interface: Plan-B pattern Material / finish: 17-4 PH stainless steel / black nitride Brake length: 1.25 inches overall; 0.42 inch added beyond the muzzle RPA profile: 0.18 inch added adapter length; muzzle device sits 0.40 inch deeper than with the standard LPA Maximum barrel diameter at brake recess: 0.750 inch Component weights: 1.2 oz per brake; 2.1 oz adapter Frequently Asked Questions Does .30-caliber bore compatibility establish a cartridge rating? No. The brakes accept bullets up to .308/7.62mm, but the suppressor must separately support the exact .300/.308 cartridge, barrel length and firearm configuration. The kit does not change a suppressor's rating. Does this package include two suppressor adapters? No. It includes two muzzle brakes and one RPA-B-SS adapter. The package supplies two firearm-side mounting points for one compatible suppressor. Does HUB threading alone guarantee fit? No. Matching rear threads are one requirement. The recessed mounting position also requires suitable blast-chamber depth, handguard clearance, barrel dimensions and caliber compatibility. Order the Comstock Armory .300/.308 Quick Detach Recessed Plan-B HUB Suppressor Mounting Kit from BattleHawk Armory. Bring matching recessed components together in one specialized package for your two compatible firearms.