Good but not great. - FAB Defense GLSHOCK AR-15/M16/M4 Recoil Reducing Stock Polymer

The idea of the extra spring for heavy recoil is fantastic. This design almost meets that. Basically if you have a commercial tube which is 1.168 inch OD this fits correctly. A mil spec tube which is 1.148 fits rather sloppy. Yes it’s only .020 but when you are fully extended it moves a lot more than the numbers show. If you are shouldering directly on the heel of the stock with a mil spec tube, it works correctly. If you are more on the toe of the stock, it binds up a little and doesn’t function as well. Of course it’s all shooter preference and how you are setup. A low optic caused me to be more on the heel is how I noticed. It is a good stock and I still bought a second one for another hard hitter. It just needs a mil spec version or a way to tighten the fit to be perfect.