Aluminum Pillar Bedding
Pillar bedding evolved out of the glass bedding that was developed to improve the accuracy and stability of wooden rifle stocks. The bedding provided a stable surface for the action to rest, but stresses were applied via wood shrinkage and swelling between the action and action screws. Aluminum sleeves were provided to provide a more stable material against which to tighten the action screws. These sleeves, or pillars, are installed either as part of a glass bedding job (primarily for wood stocks) or as a stand alone improvement (primarily for laminate or synthetic stocks).
There are three methods of pillar bedding. These methods are recessed, flush and free floating. Whatever method is used care must be taken to insure that recoil is borne by the recoil lug and not the action screws. This involves letting the epoxy holding the pillars cure with the stock in the upright position so the weight of the action bears downward.
In recessed pillar bedding, the pillar is installed in the stock solely to provide a stable surface against which to tighten the action screws. These pillars do not contact the action, but are inserted into the stock during installation short of contact with the action. This preserves an existing bedding job.
Here the pillars are installed as part of a bedding job. The pillars make full contact with the action as does the stock bedding. When done properly the portions of the aluminum that contact the action just show through the bedding. The important thing to remember that the clamping action used during the bedding process will represent the greatest holding force that can be applied between the action surfaces and the stock.
In this procedure, the action rests directly on the pillars and possibly some bedding material around them while the rest of the action free floats above the stock. Of course, the recoil lug must also be bedded to absorb recoil. Clearance is provided by wrapping the action bottom with tape except for the portions around the pillars. Note that if the Pillars are properly profiled to make full contact with the action, bedding can be eliminated so that epoxy is only used to set the pillars into the stock.
Aluminum pillars are nothing more than aluminum tubes. Most are just1/2 or 5/6th inch aluminum stock drilled on a lathe for the passage of the action screws. However, there are some salient features that should be considered, depending on which model rifle and the method of bedding.
To aid adhesion the outside surface of the pillars are either knurled or have shallow rings cut into them.
To inure the pillar won’t shift some pillars are cut with a smaller diameter towards the inside of the stock. The stock is drilled with a stepped hole so that in addition to the adhesive force an interference fit is also provided.
The two schools of thought are that either generous clearance be provided between the action screws and pillars or that the screws should be a tight fit in the pillars. Most think that generous clearance so that the pillars do not stress the action during recoil is best.
Some pillars are flat where the action screw is inserted. In those cases cap head screws are usually provided. The better arrangement is the use of screws with a 45, 60, or 110 degree head taper with the pillars countersunk at the same angle. Tightening the screws would tend to center the screws in the pillars without binding.
The pillars can be profiled to match the radius of the action to be bedded. This simplifies bedding for floating or flush bedding pillars.
Remington 700: Due to the generous surface areas available for bedding model 700s, these models are almost always flush bedded. The bedding process is usually two step with a separate build up of bedding under the tang and just behind the recoil lug, and a second bedding of the pillars. There are numerous bedding kits complete with instructions and even videos on how to bed Remington actions. For synthetic stocks with light calibers, free floating the action on pillars is feasible.
Mauser 98s: These rifles seem to benefit the least from pillar bedding. Bedding requires modifcation of bottom metal and the use of a special pillar for mating to the front of the action.
Savage 110s: On the standard magazine rifles, the rear action screw can be (depending on model) too close for easy bedding. Also, since the trigger assembly can be difficult to remove, recessed pillars are often installed for these rifles. These rifles can benefit from flush bedding in the front of the actions, especially with the economy composition stocks which are flimsy with inadequate bedding area.
The process of installing the pillars involves making sure length is right for the action screws (new or original), drilling out the existing holes, and then gluing the pillars in place, making sure that they wont contact the action screws or put stress on the action when the epoxy hardens.
The only way to insure correct placement is to install the pillars on the action, and glue the pillars in place while the action is held in the desired position. Below is a picture of pillars, as supplied in the Score Hi kit for the Remington 700 held in place prior to installation in a stock.