JMAC 4 Chamber muzzle break 5/8X24 (RRD4C)

The RRD-4C is designed to install with a shim kit on standard shoulder mount style barrels (factory muzzle device installed with crush washer) and can be permanently attached using the (optional) pin.
Product Specs:
Shims not included but sold separately 
Threads: 5/8X24 threads
Length: 2.82" long 
Only adds 1.5"
Material: 17-4ph Stainless
Weight: 3.84oz
*Not intended or recommend for barrels shorter than 10.5” (see below)