High-density polymer blocks enable the secure clamping of critical subassemblies of the SOF command assault rifle (SCAR) in a vise, eliminating the risk of crushing, twisting or distorting them. These blocks provide stable support for safe and effective cleaning, adjustment, maintenance and repair without marring or scratching the finish. They are available as a complete set or as individual components. The upper receiver/barrel block encases the front sight/gas block to securely hold the barrel module while protecting the exposed portion of the gas system, allowing unrestricted access to the upper receiver. The lower receiver/trigger module block locks into the magazine well and absorbs all clamping force, safeguarding the SCAR's polymer lower receiver from damage. One end is compatible with the 5.56x45mm SCAR-L, while flipping the block accommodates the 7.62x51mm SCAR-H. The bolt maintenance block provides the necessary support for disassembling the bolt for cleaning or repair.