Pillar Bedding Article – Part I
In the firearms industry, it seems there is always a “trend” that is accepted as state-of-the-art, atleast until something else comes along to replace it. Right now aluminum bedding blocks seemto be the trend. I recently posted our views on the ABB, so I won’t go into that now, but there isa related trend that I think needs addressing—pillar bedding or bedding using aluminum pillars.
First, a bit of history is in order. When wood stocks ruled the world, few things could improvethe accuracy of a rifle as much as glass bedding. Hardly any factory guns came bedded and mostshot barely acceptable. In general, glass bedding enhanced accuracy, as well as increased thedependability by limiting the effects of humidity and weather, which plays havoc with point ofimpact (POI). By using an epoxy-based product reinforced with fiberglass (thus the term glassbedding) you could form a superior mating surface between the stock and the receiver. Byreducing or eliminating any stresses caused by poorly matched surfaces, it allowed the rifle toshoot more consistently.
In the benchrest community, shooters found that by torqueing both guard screws with a torquewrench they could actually tune the way the gun would shoot. Shooters were constantly checkingthe torque between matches and even between groups. Most found that the more they shot theirrifle, the more the amount of torque would decrease. It was reasoned that the stocks must becompressing due to the pressure and stress associated with shooting. As a result, they drilled outthe holes around the guard screws to the next larger size (usually from 5/16 to 3/8 or 1/2 inch).Bedding the action would allow these larger holes to fill with bedding material. After removingthe screws (of course, they waxed them first), they would then drill out the screw hole to 5/16”for some clearance, but that would in effect, leave a pillar of 1/16 to 3/16” wall thickness ofbedding material. The bedding material was dense and rigid so it made a nice pillar that wouldkeep the stock from compressing under the pressure of 40-60 lbs torque, plus the stress of firingthe rifle.