Most .22lr silencers have female threads that run around .400 deep, which works on most threaded .22lr firearms. However, most .22lr conversion kits for AR-type rifles, and some .22lr firearms, have longer male barrel threads. Without a spacer, the barrel threads will protrude into the suppressor's entrance chamber, causing buildup of carbon and lead on the barrel threads, making it hard to remove the silencer. The longer barrel in the entrance chamber can also creates more erosion and leading of the first baffle. The way to solve this problem is with a precision-made threaded spacer that allows you to use your .22lr silencer on longer thread length barrels. It creates a firm, large shoulder for the suppressor to butt up against, filling the gap that would otherwise be left between silencer and barrel thread shoulder.
This Gemtech spacer is all you need to make the pieces fit on most any .22lr AR-type type carbine (including the S&W M&P 15-22, and factory-threaded Savages and Ruger 1022s, which have long, 5.56mm AR-spec threads) and works with most brands of .22lr silencers. The spacer threads onto your barrel - it's not a cheap, unthreaded spacer that falls off when the suppressor is removed - and may be installed with adhesive for a semi-permanent solution. Durable steel with wrench flats for removal and assembly, in a blued-black finish.