Create your own master
Many factory stocks come with a lot of drop and are thin and have no cheekpiece. Do you want to make your own artistic and ergonomic stock? Do it like we do and make your own master from a factory wood stock and Bondo and then have us duplicate it for you.
The advantage of creating a master for duplicating instead of carving the final piece of wood from scratch is that by creating a master you can make a mistake or change your mind and throw Bondo on it and give it another shot. It’s easy to shape a curvy rollover for example, with Bondo, then copy it into the expensive walnut, rather than trying to carve all those shapes perfect first try in the final wood.
The process starts with a factory stock as a starting point for the project. It's perfectly machined inletting of the action and trigger guard opening is best to have in the master as it is a 'first generation' of the shape. Much better to duplicate than an already copied copy. Then re-shape the pistol grip with bondo, perhaps making it more towards vertical a little bit (or a lot), adding a palm swell, etc.
To fix drop, cut almost all the way up through the aft part of the pistol grip at the beginning of the buttstock, leaving a little wood at the top, hinge the buttstock up to remove some of it’s drop (most airgun stocks are intended for iron sights use and have too much drop for scope use). Glue with shims and thickened laminating epoxy resin to hold shape, then bondo to smooth the transition.
Most often I either reshape the factory cheekpiece or remove it entirely and shape my own with Bondo. To make a cheekpiece in Bondo, use a piece of wood covered in plastic tape, or a piece of Plexiglass that is waxed. One might also use a piece of thick plastic that is somewhat flexible and has a slight curve in it naturally. I like to use 14 mil. Mylar used for vacuum bagging fiberglass. Cut the wood or plastic to the shape of the cheekpiece you want. Spread a thick layer of Bondo on the stock. Apply the plastic cheekpiece outline to the top of the buttstock at the top of edge and pivot it down squishing into the Bondo until you get the angle you want. Leave the angle a little higher than you want; it sands down to the final angle easy on the belt sander. Use a finger moistened in Acetone to shape the curve down to the buttstock around the cheekpiece. Use more bondo to shape a roll over on the back side if it's a Monte Carlo style.
Also, add to the length so we’re copying and sanding a bit longer than we need and then we can cut the length of pull nice and clean with the sliding compound miter saw.
In the case of an extremely different buttstock like say a thumbhole, bench rest or FT type stock, I might cut off the forearm forward of the pistol grip so that all we're using is just the forearm, and then glue/screw on the buttstock cut from a different stock, maybe a Boyds or Richards stock, or just a a block of wood and hand carve the new pistol grip and buttstock. Clear heart redwood is soft and knot free and works easily, but any wood will work. You can laminate several thinner pieces together to build up the width you need. Glue them together with aliphatic resin glue (like Titebond). If the buttstock is oval in shape, shape that on the belt sander then add a bondo cheekpiece. This makes it easy to create the shape of the buttstock that is ‘underneath’, if you will, the cheekpiece.
The forearm gets built up with wood or bondo as appropriate and shaped (if it gets changed at all, often factory forearms are already pretty much optimized for doing their job; it’s just the buttstocks are all wrong).
Working with Bondo:
Bondo works like soft clay and hardens through a chemical reaction that causes heat. Curing can be accelerated with heat (or slowed by cold), or by mixing with more hardener than the minimum. If you sand it flat accidentally you just put more Bondo on.
You can buy Bondo at most hardware stores (the big box stores will likely have gallon containers for not much more money than a quart at a smaller store). You can also find it at stores that specialize in auto painting and often you can find it at auto parts stores. You add a creme hardner in the ratio of about a pea size to a golf ball size of Bondo. The more you add, the faster it will kick (set). After a few mixes you'll get a feel for the color that results in a set time that you're comfortable with. I like to mix it hot enough that it will be ready to work in about 15 minutes, even if somewhat soft at that point, it will file and carve easy.
One other point about Bondo, it's part of how we pay more for things today that a quart can of Bondo will only be filled about 3/4 of the way.
I use 1/4" dowel to use as mixing sticks and Dixie type small drink cups for mixing cups. Latex gloves are a good idea too. Acetone cuts Bondo for cleanup (before it's cured of course).
Use 80 grit machine sanding belt material cut into pieces, some glued to blocks of wood with 3M77 spray adhesive, some left with their natural curve for shaping curved areas. Use a sharp wood rasp as well. Use a 3" diameter wire wheel hand held as a brush to clean out Bondo from sanding blocks and files. I prefer to use wire wheels over steel brushes because they are cheap and stiff enough to do a good job.
When Bondo is 3/4 cured or so, it shapes very very easily, but will clog paper and files quickly. Clean the clogs out as you go with the wire wheel.
I recommend as you shape the master you consider the ability to use some kind of power sanding tools as much as possible to create the master, that way you know you can sand the duplicated final stock using the same tools (curves to fit drum sanders, etc.).
I recommned these tools:
http://chainsawsculptors.com/saburr/wheels_cups/DW4125.jpg (note the url to find your way to the front page). You put them in a cheap angle grinder from Harbor Freight and use it by making smooth long strokes to remove wood. It’s super easy and fun. The wood melts away in predictable amounts almost like carving somewhat hard soap. It’s really cool. If you go too far you add Bondo to build it up. Carve the pistol grip undersize and add bondo to create the curvy palm swell shapes.
You will need a basic coarse wood rasp.
A drum sander or two of appropriate sizes for the thumb slot area for example.
A 6” belt sander is a powerful tool for shaping large diameter curves (over the rollers) and sanding the flat sides flat. They are not very expensive at Harbor Freight.
Finally, I use 80 grit belt sanding paper cut into sections and rolled into curves to work the wood in curvy areas.
It is important to add wood to the back of the buttstock to extend the length of pull. There has to be some wood to cut off to the final length of pull as the duplicator can't cut right to the final edge well. Trace the buttstock onto a piece of 2 x 4 and rough cut it on a bandsaw or scroll saw or even just a miter saw and then glue it onto the buttstock with aliphatic resin glue (Titebond for example). Then shape it to the rest of the buttstock on the belt sander.
When you think you're done paint it with spray can white primer. This will let you see just how good your final shape is. Usually you'll spot a few areas that need a bit more work.
When you've got it where you like it, send it to us for duplicating into your choice of final wood.