The T-block is part of Black Creek’s new “Tunable” Series of rifle operating parts and systems. The T-block comes in both a piston and direct impingement (di) model and both have four distinct settings, specifically designed to control (keep to a minimum) and tune the amount of gas required to run the rifle efficiently and reliably. This will prevent overgassing issues such as failures to extract, failures to feed, increased recoil, premature part wear, increased carbon build up and overall general maintenance. The T-Block has three gas port sizes, designed for various ammunition loads and suppressors, but also has a fourth “off” setting, allowing the rifle to be fired without gas, keeping the bolt from moving to the rear, reducing recoil and noise even further. The di model of the T-Block uses a straight gas tube, eliminating the heat build up and potential failure point in curved tubes when using short barrel rifles and/or suppressors. The T-block can be adjusted by hand or with any flat tipped tool and each setting is easily distinguished by an audible click and set.