Sunday, July 25, 2010

Stocks: Laminated stocks

In our last post, we talked about classic wooden stocks, which have been used through much of the history of firearms. While wooden stocks are very beautiful to look at, they have the problem of warping, distorting and cracking in changing weather conditions. This makes the accuracy of the weapon suffer. Another problem with classic wooden stocks is that many stock blanks may have to be rejected because of some minor defects (such as a crack) in the wood. This makes complete wooden stocks more expensive because the manufacturer has to reject many pieces and find perfect stock blanks with no defects at all.

One of the solutions to minimizing this problem is to make a laminated stock instead. A laminated stock consists of separate layers of wood which are glued together. If the layers are properly arranged, then they cancel out each others' distortion and minimize the warping caused by humidity, temperature etc. The result is also free of internal defects. They are also less expensive to make, since cheaper wood can be used. The same blanks that would normally be rejected for classic wooden stocks because of defects, can be used to make laminated stocks, since the manufacturer can cut multiple layers of wood from the blank by working around the defective areas.

The Germans were the first to start making laminated stocks during World War II, for Mauser K98 and G43 rifles, when solid wooden stocks suitable for rifles became difficult to obtain. The Soviets were quick to adapt this idea around 1950.

The process of making laminated stocks is the process of making very high-quality plywood. To make a laminated stock, the maker first cuts thin layers of wood (1.5-1.6 mm. thickness or so). Each layer is individually impregnated under pressure with a strong dye. Since each layer is only 1.6 mm. thick, the dye permeates every bit of the wood, which provides a high degree of water resistance. Next, a waterproof epoxy resin glue is applied to each layer's surface and they are arranged so that the direction of the wood grain alternates between the layers. Alternate layers may also be dyed in different colors to produce an attractive appearance. The layers are then put under pressure and heated to set the glue. The curing process takes a few hours to complete and the glue makes the wood cells close to the surface of each layer almost completely waterproof. The alternating directions of wood grain between the various layers give the stock extra strength. The result is an attractive stock that is stronger than a solid wooden stock and almost immune to the effects of heat and humidity.

One of the major suppliers of laminated stocks to many small arms manufacturers today is the Rutland Plywood company, which sells their raw plywood material under the trademark "Stratabond". This company manufactures stock blanks for many well known companies such as Ruger, Remington, Savage Arms, Sako, Browning, Kimber, Boyd etc. The exact lamination process and the glues used are a trade secret, but it is known that they generally use birch wood layers for their stocks and use around 35 layers of wood veneer per stock. They offer blanks in several colors and patterns per manufacturer requirements and can make customized blanks as well. Some examples are shown below.

A laminated wood stock can be almost as strong as a fiberglass stock and look and feel the same as a solid wood stock. It also absorbs vibration better than a fiberglass or an aluminum stock. A laminated wood stock has more durability and strength than a comparable solid wood stock, has zero internal defects and can be made of cheaper material as well. It is virtually immune to the effects of temperature and humidity changes, thereby retaining its accuracy in a variety of weather conditions. It also has a pleasing appearance that can rival the best quality wood stocks. The only downside is that a laminated wood stock is heavier than the corresponding solid wood stock of the same size and material.

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