Smith & Wesson M&P 22X & Compact Factory Barrel Nut Wrench

I have to second the experience of the other reviewers. I first tried a Walther wrench after filing it open a bit and only succeeded in spreading the jaws. Then came the requested, longer, but still stamped wrench from S&W, which snapped off a jaw. Then finally came Eric's TANK of a wrench, which together with 30-40 minutes in the freezer, per his suggestion, popped the thread protector loose with surprisingly little effort! When all else failed, this guy did the trick!