Time & Time Again, Makes Possible The Impossible
The only accurate way to hold barrel and receiver when aligning scope/sight screw holes if a jig is not being used and special drill press vises are not available. Set of 2 V blocks and 2 clamps.
Big Book Catalog, Issue:72, Page:425
SPECS: Cast Iron. Approximately 1½" (3.8cm) sq. x 2" (5.1cm) long.