Keep in mind that none of them actually reduce recoil but spread it out over time. First impulse when the energy from the stock goes into your shoulder, another when the piston (and bolt) stops and transfers energy into the stock/your shoulder. (Yes, the recoiling springs transform some of that into heat, but it ain't much.) Feels like less.
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Oh yeah, You loose a little energy in gas escaping through the gas ports but that ain't much either.
Last edited by nighthawk; 01/18/18.
