$75(NOW $60)($50!!) For sale is an almost new GG&G +2 magazine tube extension for a Mossberg 590/590a1. Included is the extension and the extended mag tube spring. To install, just take down the barrel, pry out the mag tube stop using a flathead screwdriver, throw in the new spring, and hand-tighten the extension on the mag tube. Easy Peasy.