Stainless steel spring is heat-treated, stress relieved and shot peened to increase reliability and service life. Spring fits both carbine and standard length stocks. Features: Bolt load is increased by 10% compared with Tubb round wire buffer springs Provides a flatter recoil impulse Requires about 6% less force to fully compress than Tubb round wire buffer springs Less than 2% change in spring loading through 500,000 compression cycles Duty rated for 1,000,000 cycles Product #: 693755