CST Rimfire Receiver: Instructions for Installation of Rear Action Screw Using Pillar Set.

CST Rimfire Receivers were designed with adaptability in mind, including the removable Threaded Rear Tab. The removable Threaded Rear Tab feature allows the ability to build your rifle without the rear action screw that can then be added later at any time, or the ability to remove the rear action screw to try the barreled-action in a different stock.

The removable feature of the Threaded Rear Tab also greatly facilitates the installation procedure as described below:

STEP-1: After cleaning the vise jaws to ensure no marks can be transferred to your receiver, clamp the barreled-action into the vise high enough that the stock can be attached without touching the vise jaws. Use parallels to locate receiver flat and… — STEP-1: After cleaning the vise jaws to ensure no marks can be transferred to your receiver, clamp the barreled-action into the vise high enough that the stock can be attached without touching the vise jaws. Use parallels to locate receiver flat and square to spindle.

STEP-2: Install the Threaded Rear Tab and indicate the threaded hole using a gage-pin or shank of a drill, (ID of hole is .177” or #16 drill). Zero and lock your mill table with the hole swept in.

STEP-3: Remove Threaded Rear Tab and clamp 3/8” diameter Endmill (or flat bottom tool) into spindle. 3/8” Endmill should be long enough to clear pistol grip area of stock.

STEP-4: Attach the stock to the barreled-action using the front action screw. May need to shim the rear gap in between the stock and receiver to prevent the stock from pushing down and flexing during cutting. Using the 3/8” diameter endmill, careful… — STEP-4: Attach the stock to the barreled-action using the front action screw. May need to shim the rear gap in between the stock and receiver to prevent the stock from pushing down and flexing during cutting. Using the 3/8” diameter endmill, carefully cut a full flat bottom into the stock.

STEP-5: Remove the stock and replace the 3/8” endmill with a 3/8” diameter Jobber-length drill into the spindle. Set the 3/8” drill to drill approx. 1/4” past the bottom surface of the Threaded Rear Tab and set your quill-stop. Make sure the spindle… — STEP-5: Remove the stock and replace the 3/8” endmill with a 3/8” diameter Jobber-length drill into the spindle. Set the 3/8” drill to drill approx. 1/4” past the bottom surface of the Threaded Rear Tab and set your quill-stop. Make sure the spindle will clear the pistol grip of the stock with the 3/8” drill at the full depth.

STEP-6: As in step 4, attach stock to barreled-action using the front action screw and shim the gap in between the stock and action to prevent flexing if needed. Lower 3/8” drill to double check clearances.

STEP-7: Carefully drill the 3/8” diameter hole, peck-drilling (in and out) to remove chips, until contact to the quill-stop at full depth. Once complete, remove stock from barreled-action and remove barreled-action from vise.

STEP-8: Place stock in padded vise and develop clearances inside the stock using a sanding bit and dremel tool. Should eat into 3/8” hole and create clearance for barreled-action with Threaded Rear Tab attached to pivot in and out of stock.

STEP-9: Relocate the stock in vise to create clearance for bottom of Threaded Rear Tab. Using the aluminum pillar allows the pillar's top surface to be used as the precision bedding surface thereby allowing the stock to be simply cleared out to not … — STEP-9: Relocate the stock in vise to create clearance for bottom of Threaded Rear Tab. Using the aluminum pillar allows the pillar's top surface to be used as the precision bedding surface thereby allowing the stock to be simply cleared out to not touch the Threaded Rear Tab.

STEP-10: Once satisfied clearances are correct, clean stock of any debris and reattach to barreled-action with Threaded Rear Tab installed as well as the trigger assembly. Tighten front action screw and check for movement at rear of stock, should be… — STEP-10: Once satisfied clearances are correct, clean stock of any debris and reattach to barreled-action with Threaded Rear Tab installed as well as the trigger assembly. Tighten front action screw and check for movement at rear of stock, should be clearances to allow slight movement. Prepare aluminum pillar by cleaning thoroughly and use release agent everywhere else metal, (Threaded Rear-Tab, Rear Action Screw, rear of receiver). Mix-up your epoxy.

STEP-11: Apply the epoxy (or bedding agent) to inside walls of 3/8” diameter hole and insert aluminum pillar. Install the rear action screw (provided in the CST Rear Pillar Set) and tighten the pillar to the Threaded Rear Tab and let the epoxy setup… — STEP-11: Apply the epoxy (or bedding agent) to inside walls of 3/8” diameter hole and insert aluminum pillar. Install the rear action screw (provided in the CST Rear Pillar Set) and tighten the pillar to the Threaded Rear Tab and let the epoxy setup overnight. The aluminum pillar is about .010” undersize from the 3/8” hole in the stock. This is to allow the epoxy to setup without the stock flexing. Once epoxy is fully cured, remove barreled-action and cleanup any excess on the inside of stock.

Finished Product: Interior bedding surface via aluminum pillar

Notes on stock material:

Wooden or laminate stocks work best with the above procedure and the Rear Pillar Set is highly recommended for these type stocks. Polymer 10/22 type stocks may not be suitable for the rear action screw or rear aluminum pillar as they are often molded with air cavities along the wrist area of the stock. The plastic material also does not allow good adhesion to epoxy when attempting to install the pillar . If there are no air cavities and there is solid material available at the wrist area of the stock, installing the rear action screw via a direct counter-bored hole into the stock without the pillar is feasible.