The pictures below illustrate 1) determining the depth of the spring mortise, 2) removal of the bulk of the wood, 3) mortise squared up with a chisel and fit for the spring lug, 4) adding the spring and clearance for the mounting screw.
The procedure shown above, that of starting with the basic major part and adding successive parts as the corresponding inlets are completed is used in all aspects of stockmaking. I like to think of this process in terms of starting with a ‘known’. For example the action of a rifle. Once properly fitted to the wood, then the action AND the wood are a ‘known’. From this point, for example, the placement and positioning of the barrel is determined. Once the barrel is fitted, any other parts related to it can be completed.
Below, a picture of the center line down the top of the comb on the buttstock illustrates the importance of maintaining these lines. Here as wood removal proceeds, it gives a reference point for the initial shaping and approximately equal amounts of material on each side.
The initial removal of excess wood can be done with a chisel or a file. I find that a chisel takes less time and effort, but care must be taken to avoid chips or tear-outs particularly in figured wood. Note in the picture below that the wood is removed in ‘layers’ along the long axis of the stock. Maintaining a degree of consistency to these ‘layers’ allows for uniform removal of wood and aids in initial shaping. When within 1/8″ or so of the proposed final shape, I like to use a Nicholson patternmakers rasp (#49) to remove most of the final wood and develop the shaping further.
Below is a picture of shaping of the nose area of the comb. A fair amount of excess wood (about 1/16″) still remains in most places with the exception of the tang area where about 1/32″ is still above the wood. When the entire buttstock is to within 1/16″ or so of the finish level, the final shaping and details will be completed.
Other related images and information
The pictures below are of a rifle that will receive final metal polishing, engraving, case hardening of the action and related parts, rust bluing on the barrel, and final wood finish. It is in 32-40 Winchester.
Close examination of the action shows minor striations and blemishes which must be polished out prior to engraving and case hardening. The desired finish for case hardening is 400, (meaning that the deepest striation in the metal is the result of 400 wet/dry paper) while 600 or finer is needed for rust bluing. Always strive to keep flat areas flat and corners sharp.
You will have to study the photo below. The picture is taken of the top of the barrel from the breech forward. Look at one of the vertical bars in the background then follow its reflection down the barrel toward the breech. Ideally, this reflection is straight and without variation indicating that there are no high or low areas over its length.