The ability to tune the system by swapping the Lifter means that the Bearing Delay system can be tuned based on ammunition type, barrel length, suppressor, or any other factor.
The typical retail package of a Mean Arms Upper includes 2 total Lifters for tuning the BCG dwell time. These components are analogous to the HK Locking piece for their roller delay systems.
- The BCG comes from the factory with the‘K’ Lifter, which should run any of the ammo that you mentioned (124, 147, etc). The K is a good middle ground. The typical retail package usually includes one additional `H´Lifter.
- The `H´ Lifter is ideal for low energy ammo (low velocity and/or low bullet weight) where the system could potentially struggle to fully cycle (your subsonic or even a low weight frangible).
- The `M´Lifter
- The `P´ Lifter is the opposite in that it is designed for hotter high energy ammo. The P Lifter will slow the cycle time, which like any firearm, is preferable for safety and longevity of mechanical components. However, moving too far in this direction of the chart (see page 44 of the Mean Arms manual) may cause the firearm to have insufficient energy to cycle reliably. The P Lifter may reduce perceived recoil. Information about the Lifters is shown on pages 42-44 of the Mean Arms manual in the box.
