Leitner-Wise’s LW 15.22 just may be the answer for those who enjoy shooting their AR-15, but have to duke it out with their wallet every time they wanna’ hit the range. Available either as a complete rifle or upper receiver replacement unit, the LW 15.22 allows you to shoot cheap-as-dirt .22 Long Rifle ammo through your favorite 5.56 "Black Rifle", so it’s easy on the wallet, and on the ears(especially at an indoor range).
Word has it that the unit functions reliably, but DefRev would definitely like to obtain one of these units for a little in-house testing.
Click here to go directly to the LW 15.22 page on the Leitner-Wise website.