of $500 or so. You dont need better accuracy than the 1.5" or so groups at 50m that the .22 unit and 223 barrel offer. Also, you have to use a dedicated "carrier' for the.22 upper when using the Ciener 22 unit in it, and when you remove the unit, the springs go everywhere! The .22 unit, used in the 223 barrel, is self-contained, no extra $30 (charged for cutting off the "retainer" end of the bolt guide).