Hammerhead

CA-Legal AR-15 Stock Adapter

Installation Instructions

BE SURE YOUR RIFLE IS UNLOADED BEFORE BEGINNING INSTALLATION.

IF YOU ARE UNFAMILIAR WITH ASSEMBLY / DISASSEMBLY OF AN AR-15 RIFLE WE STRONGLY RECOMMEND THAT YOU CONTACT A COMPETENT GUNSMITH TO PERFORM THE CONVERSION FOR YOU.  WE DO NOT PROVIDE BASIC INSTRUCTION ON ASSEMBLY / DISASSEMBLY OF AN AR-15 RIFLE.

One Minute Installation Video:

Click here to view the Nomenclature

NOTE: Please use the 1/4-28 x 7/8" screw and flat washer included with the Hammerhead. Do not re-use the screw that held in your standard pistol grip; it is too long and will not hold the product securely.
  1. Gather the Hammerhead, selector detent spring (from your lower parts kit), and fixing bolt and washer.

     

  2. Place the selector detent spring inside the tiny hole in the Hammerhead's right hand mounting tab, and pressing up against the selector detent inside the receiver. Slide the Hammerhead onto the receiver. It may be very tight and may not go on at first, if so, see below. Insert the fixing bolt/washer into the mounting hole and screw in most of the way with a 3/16" allen wrench.

     

  3. It is possible to slide the Hammerhead forward or backward slightly to adjust the fit to the receiver. Once positioned as desired, tighten securely.

     

Tight Fit to the Lower Receiver

To preserve accuracy of the rifle, Hammerhead is designed to be an extremely (insanely) tight fit to the receiver. A tight fit is far preferable to a loose fit. Hammerhead is part of your stock now, not just a place to hold on. Any wobbliness here is going to show up as degraded accuracy at the target.

In some cases it may seem that the Hammerhead is so tight that it just won't go on. But it will. There is no need to file or otherwise modify the Hammerhead.

You will use a different method rather than just slipping it on as you'd do with a pistol grip:

  1. Line up the parts as shown:

     

  2. Then push Hammerhead onto the receiver by positioning the rearmost "pointy" portion of the receiver's pistol grip attachment tab between the pistol grip tabs down as close to the ramp as possible. This is the widest portion of the Hammerhead's pistol grip mount. You may have to push and wiggle but it will go on:

     

  3. After you engage the pointy part between the pistol grip tabs, push Hammerhead further onto the receiver. This will start to spread the pistol grip tabs. Careful you don't pinch your fingers as you forcefully slide it on:

     

  4. Tilt the Hammerhead downward after you get it all the way on to open up space to insert the selector detent spring, then square it back up and bolt it on: