September 23, 2010
By Jon R. Sundra
Inside tips on how to pick the right material for your next gun stock.
By Jon R. Sundra
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.
No wood can match the beauty of fancy walnut, but from the practical standpoint it does not make the best rifle stocking medium.
I once owned a rifle where in the humid months of a Pennsylvania summer the barrel would be perfectly centered in its channel with 1/8-inch clearance all around, but in the dead of winter the stock would actually be touching the barrel on one side at the fore-end tip. That rifle went through that same cycle every year as long as I owned it.
Admittedly, that's an extreme example, but it's also the reason why so many production rifles today are set up at the factory with fully floating barrels. In my experience, soda straw barrels generally shoot tighter groups when there's some dampening pressure at the fore-end tip, but the warpage factor makes them more temperamental with regard to their ability to maintain zero. Sporter- and heavy-weight barrels tend to group and hold zero better when fully floated.
At about the same time that walnut was becoming scarce, the age of the fiberglass stock got its start. It was purely coincidental that at about the same time--the late 1960's and early '70s, the benchrest people began looking for a more stable stocking medium.
Some of that impetus was the result of another emerging concept: glass bedding. It was, I believe, the February 1957 issue of the American Rifleman that Brownell's Acraglas was first advertised. I was just a teenager at the time, but the idea that even a rank amateur could achieve perfect, 100 percent contact between wood and metal sure had me excited--enough so that upon acquiring my first bolt action centerfire rifle in the early 1960s, I immediately glass bedded it. And I've glass bedded every rifle since.
Stocks can be molded to very tight tolerances but are not thermally stable at temperature extremes. They are fine, however, within normal ranges.
As good an idea as glass bedding was, it didn't prevent a stock from warping. If glass bedding was good, wouldn't making the entire stock of fiberglass be even better?
Some of the pioneers in the field were Chet Brown, Lee Six and Gale McMillan, and it was in benchrest competition that the first generation of synthetic stocks appeared. The process consisted of taking sheets of fiberglass cloth, soaking them in epoxy, then laying the cloth in crude, half-shell molds.
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Laminates raised eyebrows when made their big debut over 20 years ago, but those stocks were nothing compared to what's available today--this Boyds' Evolution on a customized Ruger 10/22, for instance.
The external shape barely resembled a gun stock, and the bedding surface was but a remote approximation of the required inletting. Finishing one of these early examples of after-market stocks was a real nightmare, and when you were finished with it, the stock still didn't possess the proper lines and detailing because the thinness of the fiberglass shell wouldn't allow any major reshaping.
It actually took a couple of decades for the process to be
refined to where today laid-up fiberglass stocks can almost match the lines, contours, dimensions and detail that can be achieved by the finest wood craftsmen. McMillan, for example, offers dozens of styles that replicate the factory originals. The inletting is molded-in using nominally dimensioned slave forms precise enough to allow virtual drop-in compatibility.
Better yet, you can send your barreled action in and they will glass bed it in the stock of your choice. Several of the better companies specializing in laid-up stocks offer this type of service.
The most stable of stocks are laid-up fiberglass and laminated wood. Excellent examples of each are McMillan's Hunters Edge (above, top) and Boyds' JRS Classic.
Of the two types of synthetic stocks--laid-up fiberglass and injection-molded polymers--the former makes a better gun stock. Laid-up stocks are stiffer, stronger, and lighter, but on the debit side they are more expensive and lack aesthetic qualities like the warmth and feel of real wood. They feel...well, hollow and toy-like, but make no mistake: From all practical and functional aspects the laid-up fiberglass stock is far superior to wood.
They are dimensionally stable far in excess of any temperatures, hot or cold, that can be experienced anywhere on earth. The first production rifles to be offered with laid-up fiberglass stocks were Weatherby and Sako.
There is one noteworthy variation to the laid-up stock, and it was pioneered by H-S Precision back in the mid-1980s when the company was developing a stock for the Army's M24 sniper rifle. Instead of the bedding surfaces being machined or impress-molded, the stock is laid up around a hardened aluminum chassis that is precision machined to match the receiver. H-S is the only company to my knowledge to guarantee half-minute accuracy with its Model 2000 rifles, so they obviously have a lot of faith in their bedding system. Other companies have since introduced their own versions of the bedding block system.
As for injection-molded stocks, they can be quite good, depending on the specific polymer used and the mold design, which has a lot to do with overall stiffness. Once companies amortize the relatively high cost of the mold--around $50,000 on average--stocks can be spit out for a couple of buck apiece. An injection-molded stock can duplicate to the last detail the most exquisite stock ever crafted; it just depends on the model from which the mold is made.
On the downside, injection-molded polymer stocks are not
thermally stable. By that I mean they expand in high temperatures and shrink in cold temperatures. They get flabby in hot desert climes and stiffen in cold climates, to the point where they can become brittle at temperatures of 40 below. Because bedding dynamics are affected by temperature extremes, accuracy and stability of zero can change.
Last to appear on the scene was the wood laminate. Actually, the idea of gluing thin veneers of wood together for a stronger, more stable product is not new. The Germans began using laminates for their 98 Mausers when in the rush to re-arm suitable wood became scarce. Today laminates are used for all sorts of applications, including support beams for house construction.
The age of the wood laminate began in 1986 when Ruger, Savage, Thompson/Center and U.S. Repeating Arms and all showed examples of their guns set into stocks comprised of green, brown and black veneers.
Because the individual layers were so thin and of alternating color, the visual impact was quite striking, resembling the contour map-like effect you'd get with a conventional walnut stock slab sawed so as to expose the tree's annual layers at acute angles.
It was all the work of one man: Jack Barrett of the Rutland Plywood Corp., who perfected gun-quality laminates using white birch. Barrett convinced the four manufacturers to turn a few stocks using his blanks and display them at the 1986 SHOT Show. Back then the industry was a lot more conservative than it is now, and a lot of folks were taken aback at the sight of these stocks. But a lot of folks weren't, enough so that all four gun makers added a laminate to their lines that year.
The rest is pretty much history. Today, laminated wood
stocks can be found in the lines of almost every production rifle manufacturer both here and abroad.
Wood laminates are extremely stable because each veneer's grain structure is oriented differently from its neighbor, thus negating any tendency to warp in any one direction. With each layer being separated by a micro-thin layer of epoxy, the stock is highly resistant to moisture. With any kind of protective finish at all, it is virtually inert.
For those who like laminates, the color combinations are endless. Boyds', for example, offer stocks in 15 color combinations ranging from conservative all-brown to flashy multi-color jobs. Also, because laminates are indeed wood, they have that warmth of wood that feels so good in the hands and against the cheek.
On the downside, though, is the fact that a laminated stock weighs five to six ounces more than an identical stock in walnut. Because laminates are so strong, however, they can be cored out in the butt section and a mortise cut along the bottom of the barrel channel, thus shedding the excess weight.
I guess what it really boils down to is that there several materials that are both suitable and practical for stocking a rifle, but they're not equal. Some are more efficient than others; some lighter than others; some less expensive than others, and some are more pleasing aesthetically. Choosing among the options can be difficult, depending on our priorities, but at least we have a choice.
Back in the mid-1960s, when laid-up fiberglass stocks were still in their infancy, I had already embraced wood laminates over conventional one-piece stocks. In those days laminates were available only as semi-inletted blanks from firms like Herter's, E. C. Bishop & Sons, and Reinhart Fajen.
Unlike today's laminated stocks which are comprised of 1/16-inch veneers, in the "old days" the slabs were 5/16ths thick and of alter
nating blonde maple and dark brown walnut. They were pretty gaudy looking.