This Gunsmither Tools Elevating Barrel Retainer Block for the Ruger 10/22 enables the end user to precisely adjust the amount of upward pressure it puts on the barrel to eliminate the notorious barrel "droop" often encountered with factory guns. By adjusting the recessed set-screw to slightly elevate the barrel, this block increases a scope's elevation adjustment range without the need for shims, and in some cases can even free float the barrel in a properly relieved stock for greater accuracy potential. Notes: Installation of this barrel block will require minor modifications to the rifle's barrel. This is not a drop-in replacement part for the factory barrel retainer v-block.