The Gen 2 drop-in captured spring recoil system enhances your AR's performance by providing smoother, quieter operation without requiring permanent modifications. The custom-ground buffer spring, paired with the JP LMOS buffer, significantly reduces friction and vibration, eliminating the harsh "spoon over a cheese grater" noise typical of traditional springs and buffers. This system is compatible with both M4 style collapsible stock buffer tubes and longer tubes for fixed rifle stocks when using the included spacer. The H2 buffer, which is heavier than the standard, features two Tungsten weights and one steel weight, totaling approximately 4.7 oz. Ideal for short-barreled rifles, suppressed firearms, select fire rifles and piston-operated rifles. For further optimization, the Auxiliary spring Rate kits allow for precise tuning, particularly beneficial for rifles without adjustable gas blocks. The newly designed aluminum guide rod reduces the overall weight Increased mass results in greater buffering capacity and a higher likelihood of bolt bounce Complete correspondence exists between SCS masses and the H1, H2 and H3 buffers