There was a time not very long ago when a rifle stock was pretty much synonymous with wood. It could be any type of wood, but in most cases--particularly with bolt action rifles--it was a single piece of walnut.

There are several reasons why walnut came to be the chosen medium for stocking a rifle: It was strong yet relatively light in weight; it had a dense-enough grain structure to hold embellishment such as fine-line checkering and carving; and in its fancier grades it possessed a degree of color, figure and depth that few if any other woods could match. Moreover, no matter how plain or fancy the figure and grain pattern, no two were the same, so each stock was as unique as a fingerprint.

But walnut is not without its drawbacks. For one thing, it started to become scarce enough by the late 1970s that some manufacturers started using less desirable but more plentiful hardwoods like sycamore and birch for their less expensive guns. From the aesthetic standpoint these relatively plain woods had little to offer, but they made perfectly serviceable stocks.

Aesthetics aside, however, there is another function a gunstock must perform other than serving as a handle, if you will, and that is to provide a stable pressure dynamic between it and the barreled action. Truth be told, a one-piece stock--be it of walnut or any other suitable wood--is not the most stable material in the world.

Wood swells and shrinks depending on its moisture content relative to seasonal humidity. Have you ever found your rifle's stock screws to change from being tight to loose, or vice-versa? Or that at certain times of year there's a seamless juncture between the butt of your rifle and the recoil pad or buttplate, but at other times there's a noticeable step? That's because the wood has taken on moisture and swelled in relation to the pad or plate, both of which are inert.

Injection-molded stocks average about the same weight as walnut ones. Neither can match the laid-up stock in terms of weight, though.

If every square millimeter of a stock is thoroughly coated with a good water-resistant finish like polyurethane, a stock can be highly stable. I mean all surfaces, including the inletting, beneath the buttplate and checkering panels if present. Most production rifles, however, are not that well weatherproofed, and those that are checkered often have no protective finish at all in the panels because it clogs the grooves and rounds off all the tiny surfaces that otherwise provide a non-slip grip.

Imagine how much the pressure can build up if a stock swells by .025 to .030 inch, which is not a lot. If that particular stock was bedded at the factory so there was, say, five pounds of dampening pressure at the fore-end tip, that could easily double or triple--changing point of impact. I've had rifles shift point of impact by four inches depending on time of year.

But there's more to it than the simple swelling or shrinking; an even worse problem is warping. As a stock dries out, it will warp away from what would have been the center of the tree trunk from which it was cut; as it takes on moisture, it moves toward the center of the tree. The only way we can observe stock warpage is with a fully floating barrel where there is a gap along the sides and bottom of the barrel. Looking at the tip of the forearm, the barrel should be centered in the "U" of the channel.