Drop-In Kit Converts A Stock Lower Receiver To Accept A Sub-Caliber Upper
One-stop, drop-in solution with the parts you need to convert a mil-spec small pin (.154" dia.), .223 lower receiver with collapsible stock to accept a 9mm upper receiver assembly. Kit includes a replacement hammer, recoil spring, and buffer optimized to handle the reduced recoil force of the 9mm Luger round, as well as a Magwell Conversion Block that installs in your rifle’s magazine well to allow it to accept Rock River’s 25-round 9mm magazines, available separately. To use the Kit on a full-size rifle with fixed A1/A2-style buttstock, install the separately available Delrin® Spacer in buffer tube behind recoil spring.
AR-15, Issue:11, Page:009
Big Book Catalog, Issue:68, Page:010
SPECS: Hammer & Buffer - Steel, matte black oxide finish. Action Spring - High tensile strength spring steel. Magwell Conversion Block - Steel with matte black oxide finish and aluminum with matte black, hardcoat anodized finish. Fits CAR-15/M4 collapsible stock models with .154" diameter receiver pin holes. Spacer – Machined Delrin. 2-1⁄8" (5.4cm) long. Fits buffer tube for standard, fixed A1/A2-style AR-15/M16 buttstock. Not included in kit; must be purchased separately.