Dec. 23, 03

Light Varmint BR Stock Construction

The rifle is a cal 6PPC with a Viper action left port right bolt, Jewell 1.5oz trigger, 36x B&L scope in Stiller rings and Shilen 1-14" barrel.

Since I never build a stock like that before, I had to gather a great deal of information on the weight of the material and where to get it. Weight of course is the most important consideration because the total weight of the bare stock should not exceed 22oz if some counterweight is added and the shape must conform to IBS specs. The total finished stock weight came in at 28 oz including a 10oz make up lead weight at the very back and bottom of the stock. The total finished weight of the rifle is 10lbs-7oz.

 According to the information I gathered the stock should be strong but not too stiff must resist lateral torque and bending, have a low center of gravity, with the best moment of inertia possible. (Resist rotation). The exterior shape I got from pictures

 I started with full size drawings, section and detail each with weight calculation. I had some help from Dan Hackett with the forearm design and shape. The shape up to the pistol grip is that of a truncated cone 3" wide on the bottom and 2.200 on the top 1.736" deep at the forearm tip and 2.039" under the action.

 The stock is set up perfectly level in both directions and a centerline is marked on the stock. The action is set on three adjustable wood screws so it too is level in both directions and centered in the stock. The bottom of the action is then bedded with a solid mix FRR. After that the action is bedded with Brownell Steel Bed. One thing about this job you do a lot of sitting down and looking thinking what to-do next, and that epoxy glue don't come apart when you screw up. How much did it cost? I did not keep track of all the bits and pieces, about $125 Canadian

The two forearm compartments are later filled with

Styrofoam and glued in place.

The basic construction is Balsa wood boards, 8oz carbon

fiber cloth, 12oz S-glass fabric, structural grade high-density styro foam and System 51 epoxy resin.

Balsa wood is one of the lightest woods available it grows in South America. The density is from 6-12 LBS. per cub/ft. It comes in selected grades for selected weight you pay a bit more. I selected a density of 10 lbs. Boards are 3" wide and 3-0ft long 3/16 thick

The 1/8" sidewalls and partition are glued in place.

Waxed paper is used for epoxy isolation. Cloth pins are used to glue the top rail to the board to make up the top with of the forearm.

Styrofoam Fore-arm fill. 

Six blocks of structural grade SR grade 40 Styro foam are fitted and epoxy glued into the forearm. The outside receives a single layer of 12oz S- glass fabric and the butt gets two layers. The forearm has three bulkheads and 1/4" corner strip in the bottom and a 1/4x3/8 top strip on each side to make the width on top. The cavity is filled with split pieces of styro foam and shaped. After the shaping a layer of carbon fiber is glued on top of the foam to form the barrel channel with ample air around the barrel. When the forearm sits level on the front rest so will the scope and action

The bottom 3/16 board runs all the way from the front to the back and has carbon fiber 8oz fabric laminated with 51 System Epoxy on both sides and bents up 3/10" in front of the action to the tip. Two additional boards run from the front of the action to the back of the stock and one more board under the action. These boards are shaped to suit the angular inside space. Two 1'4" hard wood dowels a drilled and glued into the boards behind the action to hold a solid resin and ground-glass-mix-block to form a recoil stop for the action. This also provides an additional bond between the laminations.

Pistol grip and continuous laminated Balsa boards with carbon fiber layers

Two blocks of structural grade SR grade 40 Styro foam are glued to the board extensions to form the butt. The forearm receives a single layer of 12oz S- glass fabric and the butt gets two layers.

Metallic automotive paint. At present the action is held in place with three ½' pillars and three guard screws. The stock has a temporary paint job and needs a lot more finishing. The stock comb is a bit too fat and so is the bottom I think, but I will find out when I shoot the rifle. Sanding resin and fiberglass is bad and flies all over the house and not good for your lungs. It is advised to work only with a dust mask when sanding this stuff. Next winter will be the time to make the changes and get a nice paint job. 

Fred the Reloader and Wildcatter

w.ca

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