On the other hand, the thread adaper thing should not really do any damage that would void the warranty...
search for > "Smith & Wesson M&P15-22 Threaded Barrel End for Non-Threaded Muzzles" < only costs $30.00
Then attach a flash suppressor. But do you want that chunk of metal hanging off the end of your barrel?
But,,, if you look at the "Colt M4 .22 Barrel Thread Converter" it would probably work and looks a heck of a lot better and almost like the real deal on the real M4 style weapon (somewhat) and its only $25.00
Tacticool,com also has the same "Colt M4 .22 Barrel Thread Converter" but its $30.00 .... and also has the "Smith & Wesson M&P15-22 Threaded Barrel End for Non-Threaded Muzzles" for $30.00
Don't know if the "Colt M4 .22 Barrel Thread Converter" would work on the 15-22 though, but it does look nicer then the other thing and $5.00 cheaper at the
http://www.mp15-22,com/products/colt...cessories.html