Installing Bedding Pillars Reprinted From Benchtalk
By Bob Brownell
Bedding with synthetic materials has been, for many years, accepted as a key element in the building of accurate rifles. The proper use of synthetic bedding compounds is essential to providing a stable, stress-free platform to support the rifles’ receiver when it is attached to the stock. Without this stable attachment, your shot-to-shot consistency and accuracy will suffer. But, synthetic, or ‘glas bedding alone may not always fully compensate for the wood’s natural tendency to move.
Accuracy-minded shooters are a curious and industrious lot. If something can be done to shrink groups, someone will spend months and years thinking up new techniques and then even more perfecting it. This is especially true within the benchrest community. The free exchange of ideas and information between the competitors in this game is truly phenomenal. One of the “gifts” the benchresters have bestowed upon the rest of the shooting community is the practice of pillar bedding.
As a wood stock absorbs moisture from the air, the wood fibers naturally expand. But, when these wood fibers are bound by the pressure of the action screws, the fibers are forced to compress. As the moisture level in the air falls, the compressed wood fibers shrink away from the metal components resulting in loose action screws. Repeated tightening of the action screws will eventually result in the bottoming out of the top and bottom metal against the mag box or, in extreme cases, interference with the bolt as the screws come up through the action. Either of these conditions result in a poor fit between the receiver and the stock, even with conventional, synthetic bedding.
Pillar bedding, used along with regular 'glas bedding, overcomes this expansion and contraction of the wood fibers. Pillar bedding is the insertion of hollow metal tubes glued solidly in place around the front and rear action screws. These tubes, or “pillars”, effectively control the compression of the fibers by maintaining the proper spacing of the triggerguard and receiver throughout the life of the stock.
In order to do this job properly, these pillars must be straight and in line with the action screws which need to be cut to length and installed so they do not put any stress on the receiver.
To get the best results, many gunsmiths have recommended bedding in two separate stages. Having the pillars in the stock before you begin the actual bedding job allows you to remove a thicker layer of wood and get more bedding material into the stock. The first step is to open up the action screw holes to accommodate the pillars. The best tool to use for this is a piloted counterbore.
By matching the pilot size of the counterbore to the guard screw holes, this tool will enlarge the action screw holes perfectly in line with the original hole. Open up the hole 1/16” larger in diameter than the pillar so the pillar will slide in without any interference. This is essential for a stress-free installation.
After opening up the action screw holes, use the original action screws to attach the pillars to the action. Place the action into the stock and check for adequate clearance between the pillars and the stock. A rat-tail file can be used to relieve any contact between the stock and the pillars. When the barreled action will assemble easily into place, I mark the portion of the pillar that protrudes from the bottom of the inletting with a pencil. This mark indicates where the pillar must be trimmed for correct length.
The next step is to face off the pillar that was just marked. This can be done in a lathe or done manually with the Brownells 90° Barrel Facing Tool (#080-943-000) and the appropriate pilot. Try to select a bore pilot that will match the inside diameter of the bedding pillar as closely as possible. An example of this is the .308 bore pilot (.298” outside diameter) that works best on Brownells Pillar Bedding Sleeves that have a .302” inside diameter. Trim the pillars to fit as flush with the stock as possible, but leave one of the pillars a little too long to compensate for inletting that may be a little too deep. This is especially common with Remington and Sako brand firearms. Be sure to check the existing bedding depth and trim the pillars appropriately.
Installing the pillars is now a simple task. Brownells Acra-Release™ (#081-028-000) is applied to the action and screws. The pillars are cleaned, roughened and reattached to the bottom of the receiver using the action screws. All of the parts are then “dry” assembled into the stock to check alignment and fitting. If the alignment and fit are correct, Brownells Acra-Quick Gel™ (#081-000-025) is applied to the holes in the stock and to the pillars themselves. The entire action and pillar assembly are lowered into the stock and held in place with a snug wrapping of Surgical Tubing (#084-076-001). By first gluing in the pillars while attached to the action, you assure yourself of a perfectly aligned fit.
By following these tips you should be able to install pillars in your stock that will complement and complete your best synthetic bedding jobs. If you have any questions regarding these instructions, please feel free to give our Gun Tech team a call or e-mail us your questions. We’re here to help!