Pillar bedding a rifle

May 16, 2016Bill MarrGunsmithing0

A well bedded stock is an essential part of an accurate rifle. Pillar bedding helps ensure accuracy as conditions change.

Historically, when rifles were equipped with wood stocks, as the wood expanded and contracted with changes in humidity and temperature, the point of impact and accuracy of the rifle was effected. Bench rest shooters would use torque wrenches to ensure action screws were at the appropriate settings between strings. Drilling the action screw holes over sized and filling the voids with bedding compound, improved accuracy. Some of these shooters figured out that placing sleeves made out of metal tubes, or pillars, in the action screw holes would allow the action screw torque to remain constant and provide superior results to those stocks without them (check out this article from McMillan the history of pillar bedding and how it works).

Pillar bedding is common in wood, fiberglass and plastic rifle stocks. In addition to helping the rifle maintain accuracy, the pillars provide consistent spacing between the action and bottom metal which is necessary with modern detachable magazine systems.

Bedding pillars are found in different materials and thicknesses. Aluminum is the most common, but steel, G10 and epoxy can be encountered. While most are 9/16″ or 5/8″ in diameter, some, like those found on some factory Savage rifles, can be thin tubes.

Bedding pillars are a big help in wood stocks. Some fiberglass stocks can benefit from them as well. If the material in the core of the stock can compress, it would benefit from pillars. Pillars are not needed if a stock has a metal bedding block- occasionally you’ll hear about a smith trying to do this, I wouldn’t.

In this post, we will be pillar bedding my friend’s Remington 700. Assembled from an old Remington 700 action that was screwed to a newer 700 take-off barrel chambered in 22-250, it is a little rough around the edges. The fiberglass stock is a used Bell and Carlson that was previously bedded. Not an ideal scenario for a bedding job, but one that can work.

Pillar bedding a wood stock is a similar process to the fiberglass stock shown here, but some of the techniques and materials would be different. I’ll explain the differences in the techniques needed for a wood stock throughout this post.

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Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

For this project, I ordered the following parts fromBrownells:

The first thing I like to do is see how all of the parts fit. To do this, I assemble the unloaded barreled action in the stock to make sure the clearances are appropriate.

To check the fit of the barrel in the barrel channel, I moved some paper down the barrel channel. Note in the image above it caught on a high spot. This will need to be taken down a bit.

I use abarrel bedding tool (shown above) and sandpaper to clean out the barrel channel. If you don’t have the specialized tool, simply wrapping sandpaper around a dowel or socket will work. Since this is a used stock, any existing compound from the previous bedding job should be removed at this stage of the process.

Take a look at theBrownells catalog and you will see a wide variety ofpillars. Some are adjustable, some are synthetic, some are precut. The aluminum pillar we will be using in this post are sold asBrownells pillar bedding sleeves. Note these 9/16″ diameter pillars have a radius cut in the top to match the bottom of the rifle’s action. I coated the bottoms of the pillars with some redDykem so I can mark their length later in the process.

There are a few options to drill the holes for the pillars. In this post, I’ll be using theScore-High fixture (above), however, a hand drill with a piloted counterbore, drill press or milling machine would all work. A fixture like this would only be worth buying if you had a few different rifles to work on.

The fixture sits inside the top of the stock. A tapered pin is used to locate the front action screw.

The bottom plate is installed in the bottom of the stock and a 9/16″ drill bit is used to cut the rear pillar hole.

The process is repeated from the front pillar hole.

The finished hole for the pillar.

These pillars need to be cut to length. Note the excessive protrusion.

To mark the pillars to length, I need to make sure they are properly seated against the action. I place them in the stock and ensure the concave surface of the pillar is in line with the action.

The action is placed in the stock so the pillars are seated against it.

The stock is flipped upside down and a scribe is used to mark the pillars to length.

I cut the pillars to length on a lathe. A hacksaw and file would work as well if you don’t have access to one.

The rifle can now be prepped for bedding. The bolt and trigger are removed from the barreled action and the steel is degreased (I wipe it down with alcohol on a clean rag). Only the rear surface of the recoil lug should contact the bedding. The sides and front of the recoil lug are taped to accomplish this. I use 3M fine line tape for the sides. This is an automotive painting product that works extremely well for this task.

Voids in the rear of the action are packed withmodeling clay. I sprayrelease agent BEFORE packing it withclay. This will make clean up easier.

Theclay is cleaned up with a razor blade. This will help prevent a mechanical lock when the bedding compound is applied. I also make a smallclay “snake” to place in the stock, just in front of the recoil lug area to prevent epoxy from flowing forward.

The metal parts are coated in more release agent. I have foundAcra-Releaseworks the best. Alternatively, clear shoe polish or paste wax can be used.

All stock surfaces are degreased prior to applying the bedding compound. I prefer to useMarine-tex for fiberglass stocks. For wood stocks, I prefer Acraglass. To mix theMarine-tex I purchased some mixing cups from an automotive paint store that work well, they cost about $0.30 each and are certainly worth it. Note the clay “snake” (mentioned earlier) on the stock in the background.

The surfaces of the stock and pillars are coated inMarine-tex.

The bottom metal is taped to the bottom of the stock and the action is set in thecompound. I normally use the factory screws to attach them. Long bedding screws are sold if you don’t want to use the ones that came with the rifle. I would only use the bedding screws if the action screws had a slotted head. The hex head screws (coated in release agent) are easy to remove from most bedding jobs.

The excessepoxy is cleaned up with cotton swabs, a razor blade and some alcohol. To allow the epoxy time to cure, I hold the rifle’s barrel by a padded vise and let it sit overnight.

$dried marine tex pillar bedding$

The screws are removed and the action is tapped with a block of nylon to remove the barreled action. This is what the surfaces look like.

I clean up the excess bedding material on the mill, however, sand paper and files work just as well. Again, you don’t need the fancy equipment I am using here.