Extra power buffer spring The Extra power buffer spring by SpinCo represents a significant advancement in AR buffer spring technology, originally developed in 2006 to meet the rigorous demands of a Force Modernization Team. This spring was specifically engineered to enhance the reliability and performance of M4 carbines operating under challenging conditions in the Eastern Asia Theatre. The Red spring variant is designed with a load capacity approximately 25% greater than the White spring, addressing specific load Constants in its design. This increased load capacity ensures superior performance and reliability, particularly in high-stress environments. Ideal for use in a variety of calibers, the Red spring is commonly employed in 9mm, 6.8 SPC, 6.5 Grendel, .450 Bushmaster, .450 SOCOM, .500 Beowulf and Colt LE6920 carbines. However, it is important to note that individual firearms may exhibit variations based on port values and the power factor of the ammunition used. For optimal performance, users are advised to consult the provided tuning procedure reference documents before seeking further recommendations. This ensures that the Extra power buffer spring is perfectly matched to your specific firearm setup, delivering unparalleled reliability and function. The AR .308 Cal pattern carbine CS spring kit, developed by Sprinco USA, is engineered to resolve reliability issues commonly encountered with M4 carbines, particularly during operations in eastern Asia The red spring included in the kit offers approximately 25% greater load capacity compared to the white spring, thereby enhancing performance across various calibers Users are advised to consult the tuning procedure reference documents prior to requesting recommendations for the spring's application with specific firearms and ammunition loads