Been showing these adjustable butt pads on my guns for a few years now and often get questions about how I install them so thought I'd finally elaborate! This is how I measure, grind and install Bisley adjustable butt pads.
1. Brand new Bisley adjustable butt pad assembly is comprised of a rubber pad with a nut, an aluminum backing plate secured to the pad with two screws, an aluminum base plate and large screw.
2. Start by unscrewing the brass colored nut in the hole in the middle of the rubber pad. Do not lose the nut, it can sometimes fall out.
3. Separate the rubber pad/ backing plate from the base plate. Note the location of the two screws securing the backing plate and the rubber pad together (black arrows). These screw into threaded metal fasteners inside the rubber pad. If at any time the brass nut inside the rubber pad turns sideways, separate the rubber pad and the backing plate by unscrewing the two screws, correctly orient the brass nut and reassemble. Remove the brass colored screw that slides up and down in the base plate and set the screw aside (green arrow).
4. Next determine if you need to drill new screw holes in the butt of the stock. Stand the muzzle (or end of the stock if you remove it) on something soft and set the butt pad assembly on the butt. It is important that the assembly is close to centered between the heal and toe of the stock. You'll want to grind as close to equal amounts of rubber off off each end (heel and toe) of the pad. If the pad is too far one way or the other you may end up grinding off too much and expose one of the threaded fasteners inside the rubber pad.
5. Next, using a straight edge, adjust the position of the assembly so the underside of the stock lines up with the toe of the rubber pad. Don't try to take a short cut by positioning the assembly so you only have to grind one end....remember the threaded fasteners!
6. Lift the rubber pad/backing plate off the base plate and compare the locations of the pre-drilled screw holes in the base plate with the locations of the factory drilled screw holes in the stock Chances are they will not line up and you will have to drill new screw holes in the stock. In all of my installations the pre-drilled hole in the toe of the base plate is too close to the toe of the stock as indicated by the pencil in the photo. Installing a screw through this hole risks cracking the toe of the stock. I drill a new screw hole in the base plate approximately where the arrow is in the photo.
7. If you drill a new screw hole in the the toe of the base plate use a drill bit only slightly larger in diameter than the diameter of the screws you select to use. Drill the new screw hole in the base plate from the BACK approximately where shown.
8. Turn the base plate over and, using a drill bit similar in diameter to the head of the screws you select, drill a shallow counter sunk hole in the face of the base plate. Drill just deep enough so the screw head lies flush. Use flat head screws not dome head screws. If you use a drill press, clamp the base plate in place to eliminate drill bit chatter which can result in an out-of-round hole. The base plate is weakest around the cut out slot so don't use so much clamping force that you bend the plate.
9. Screw fits flush in correct depth counter sunk hole.
10. Set the assembly back on the stock and check alignment again.
11. Lift off the rubber pad/backing plate without disturbing the position of the base plate. Using a pencil mark the location on the stock of ONLY the pre-drilled screw hole in the HEEL OF THE BASE PLATE. Don't worry about the screw hole in the toe of the base plate right now.
12. In the event you encounter something like this and cannot reposition the base plate, plug the screw hole in the stock by gluing a dowel or whittled piece of round wood in the hole. Cut the plug off flush with the face of the stock when the glue dries and drill your new screw hole.
13. Lift the base plate off the stock and, using a drill bit of appropriate diameter for the screws you select, drill a new screw hole in the heel of the stock being careful to keep your bit square with the face of the wood.
14. Install the base plate securely with a screw through the HEEL. Now, insert your drill bit through the hole you intend to use in the toe of the base plate and, using the base plate as a guide, drill a hole the appropriate depth into the stock. Securing the base plate at the heel and using the plate as a guide to drill your toe screw hole will prevent the drill bit from wandering in the wood, assuring both screw holes in the stock line up with both screw holes in the base plate (see hint below). Be sure the screw you use in the toe is not too long and do not drill the hole too deep or you risk the drill bit coming through the underside of the stock. DO NOT ATTEMPT TO MARK AND DRILL SCREW HOLES IN THE HEEL AND TOE OF THE STOCK AT THE SAME TIME. HINT: for the screw hole you're drilling in the toe of the stock, start with a drill bit the SAME DIAMETER as the screw hole in the aluminum base plate and drill into the wood 1/64 inch. The pointed tip of the drill will be perfectly centered through the hole in the base plate and the taper the tip leaves in the wood will act as a guide and perfectly center the smaller drill bit you finish with.
15. Now install the screw through the toe of the base plate so the plate is secured at both the heel and the toe.
16. Outline the contour of the stock on the back of the base plate with a sharp pencil or the back of the tip of a pointed knife and remove the base plate. I prefer scribing a fine line with a knife as it allows me to make a more precise grind more quickly matching the contour of the stock than grinding to a thicker pencil line.
17. I use a bench sander and 120 grit aluminum oxide paper to do my grinding. Some people use a stone grinding wheel but in my experience aluminum quickly clogs the stone. Note that I glued a piece of file folder to the sander to cover the grooves. This prevents the little bumps on the face of the base plate from hanging up and allows a fluid motion of the base plate across the sanding disk.
18. With the base plate FACE DOWN begin grinding the aluminum away until you reach the contour line. Use a continuous, fluid motion to prevent grinding flat spots in your edge. STOP GRINDING THE EDGE BEFORE YOU REACH THE TOE OF THE BASE PLATE. The toe needs to be ground at an angle to match the angle of the underside of the stock discussed in No. 5 above and you cannot accomplish that with the base plate laying flat and the sander.
19. Holding the base plate in your hand, grind the required angle on the toe of the base plate carefully. I accomplish this by "eye balling" the angle. The toe is the most difficult grind to get correct.
20. When you have ground as close to the drawn or scribed contour line on the base plate as you can, screw the base plate to the stock and check for fit. I use a felt pen (a dry erase marker is wiser than the permanent Sharpie I used in the picture) to highlight any places along the edge of the plate that stand proud above the stock and require more grinding. Remove the base plate, grind off the ink, re-attach and check for fit. Remember, it is better to take too little material off the edge and have to repeat the above steps than to take too much off. I usually repeat this grind-install-check-remove-grind procedure half a dozen times before I am satisfied with the fit.
21. When the base plate matches the contour of the stock to your satisfaction, remove the base plate from the stock and assemble with the rubber pad/backing plate using the brass colored screw and nut. The base plate will now serve as the template for grinding the rubber pad/backing plate. Begin grinding the rubber pad/backing plate (red arrow) to match the contour of the base plate (green arrow). DON'T FORGET TO STOP BEFORE YOU GET TO THE TOE. This takes patience and a sharp eye and is best accomplished with back lighting so you can see what you are doing. Do not grind so much off the rubber pad/backing plate that the edge of the base plate contacts the sanding disk. If it does your base plate may no longer match the contour of your stock perfectly.
22. When you are ready to grind the toe of the rubber pad/backing plate, FLIP THE ASSEMBLY OVER and eyeball the angle to match the contour of the base plate. Again, the toe is the most difficult grind to get right.
23. This is what a finished Bisley adjustable butt pad looks like.
24. This is what it looks like installed. Note that 120 grit sand paper will leave marks in aluminum. I often take the components apart off the stock and dress up the aluminum edges with fine sand paper, just be careful not to round the edges or take off too much.
If I could change anything about the Bisley adjustable butt pads it would be to eliminate the pre-drilled screw holes in the aluminum base plate so I could drill my holes where I want them.
Hope you enjoyed. Give one a try.
