Disclaimer: The content provided in this article is intended solely for informational purposes and is expressly designed for use by trained and experienced gunsmiths or individuals with advanced technical knowledge in firearm accurizing. Any application of the techniques, materials, or processes described herein carries inherent risks, including but not limited to damage to firearms, personal injury, or property damage. Redleg Company, its owners, agents, and affiliates assume no liability for any direct, indirect, incidental, or consequential damages resulting from the use or misuse of the information provided. The reader is solely responsible for ensuring compliance with all applicable local, state, and federal laws governing the handling, modification, and maintenance of firearms. All firearm work should be conducted with the utmost caution, and it is strongly recommended that individuals unfamiliar with these processes consult with a certified professional. By proceeding with the instructions or suggestions outlined in this article, the reader acknowledges and accepts these risks.
Introduction
Pillar bedding has long been recognized as a crucial step in maximizing a rifle's accuracy. While many understand that properly pillar-bedded rifles tend to shoot better, the underlying reasons are often less clear. What makes a couple of metal tubes and some epoxy so transformative for a rifle's performance? More importantly, what does "correctly" pillar bedding entail, and how can one ascertain if a bedding job meets the highest standards?
In this comprehensive guide, we will delve deep into the intricacies of pillar bedding. We'll explore why it's essential, how it enhances accuracy, and the meticulous steps required to execute it flawlessly. Whether you're refining your skills or seeking to understand the nuances of this critical process, this article aims to provide valuable insights for the master gunsmith.
Understanding Factory Bedding Systems
The Limitations of Mass Production
Factory rifles are designed for efficiency and profitability. To maintain high production rates, manufacturers often prioritize ease of assembly over precision fitting. Stocks are machine-inletted to accommodate a wide range of barreled actions, resulting in a loose fit. Many standard stocks feature a pressure pad at the fore-end, applying upward tension on the barrel when the stock screws are tightened. While this method achieves acceptable accuracy for the average shooter, it falls short for those seeking exceptional performance.
Factory Improvements and Their Shortcomings
In response to increasing demand for accuracy, some manufacturers have begun free-floating barrels and employing rudimentary bedding techniques. Methods include:
Spot Bedding: Applying bedding compound around the recoil lug and rear tang.
V-Block Bedding: Integrating a V-shaped bedding block into synthetic stocks.
Pillar Installation: Incorporating pillars into stocks without full bedding.
While these methods offer marginal improvements, they often lack the precision and stress-free fit required for top-tier accuracy. The mass-produced nature of these solutions means they can't match the benefits of a custom, meticulously executed bedding job.
The Science of Accuracy
Controlling Barrel Movement and Vibration
At its core, achieving superior accuracy involves minimizing barrel movement and vibration during bullet travel. Key factors contributing to this control include:
Rigidity: A stiffer rifle experiences less movement. Heavy bull barrels and solid single-shot custom actions exemplify this principle.
Material Stability: Custom barrels with consistent bore tolerances vibrate less than factory barrels.
Stock Design: Rigid stocks, whether laminated wood or quality synthetics, reduce flex compared to flimsy alternatives.
By ensuring that the action and stock form a unified, stress-free assembly, we effectively create a more rigid platform. This rigidity translates to consistent barrel harmonics, essential for precision shooting.
The Role of Pillars
Pillars prevent stock compression between the action and bottom metal. During firing, vibrations can cause slight stock compression, leading to action movement and decreased accuracy. Pillars, typically made from aluminum or stainless steel, provide a solid connection point, reducing this movement. Custom-made pillars ensure exact fitment, further enhancing stability.
Identifying and Eliminating Action Stress
The Importance of Stress-Free Bedding
A stressed action can significantly hinder accuracy. Stress occurs when the action is bent or twisted upon tightening the stock screws, altering bolt lug contact and affecting barrel harmonics. To achieve top accuracy, the action must remain as straight and stress-free as possible within the stock.
Testing for Bedding Stress
To gauge bedding stress:
Setup: Secure the rifle with the barrel free-floating.
Measurement: Use a dial indicator on the barrel ahead of the fore-end.
Procedure: Loosen and tighten the front action screw.
Observation: Any movement indicates stress. There should be zero movement vertically or horizontally.
Even minor stress can impact bolt lug contact, altering the action's performance. It's essential to detect and rectify these issues during the bedding process.
The Pillar Bedding Process
Preparing the Stock and Action
Remove Interferences: Eliminate any pressure pads or contact points in the barrel channel. If the stock can accommodate it we like to see a gap of .020” on the side and .060” on the bottom of the barrel channel.
Drill Pillar Holes: Enlarge the action screw holes to accommodate the pillars, ensuring at least a 1/16" clearance around the pillars.
Fabricate Custom Pillars:
Use aluminum bar stock for optimal stability.
Cut pillars slightly (.005") longer than the bedding depth to prevent stock contact.
Inside diameter of the holes should be about .020” bigger than the outside diameter of the screws.
Verify the height is proper, check feeding, and magazine fitment.
Roughen and degrease the pillars to enhance epoxy adhesion.
Inletting for Bedding Compound
Stock Material Considerations:
Wood Stocks: Remove 1/8" to 1/4" of material in the bedding area to allow a thick epoxy layer, mitigating wood movement due to environmental changes.
Laminated/Synthetic Stocks: Remove 1/16" to 1/8" as they are inherently more stable.
Maintain Proper Height: Leave a piece of the stock at the rear tang area to maintain height. Tape wrapped around the barrel will center the barrel in the channel and be used to hold up the front of the firearm on the next step.
Surface Preparation: Roughen and degrease the interior bedding area to promote epoxy adhesion.
Action Preparation
Disassembly: Remove the trigger, safety, bolt release, and magazine components.
Taping: Apply tape to areas where epoxy should be excluded, such as the sides, bottom, and front of the recoil lug.
Wrap tape around the barrel near the end of the forearm to support and center the barrel in the channel.
Clay: Modeling clay is not always necessary but can fill in areas of the receiver you don’t want epoxy to flow into.
Release Agent Application: Use a thin layer of high-quality release agent (e.g., Brownells Acra-Release, kiwi shoe polish) on all metal surfaces that will contact epoxy. Avoid thick agents that can impede a tight bedding fit.
We also apply release agent or kiwi wax to the action screws.
Bedding Procedure
Epoxy Mixing:
Use high-quality epoxies like Accra-Glass, Marine-Tex, or other firearm bedding compounds.
Read and abide by the directions for mixing proportions according to the manufacturer.
Mix thoroughly; when you think it's enough, mix a bit longer to ensure proper curing.
Colors can also be applied to certain manufacturers epoxy at this time. We add dye after so we can see that the epoxy has been mixed properly the dye may hide that if done at the same time.
Pillar Installation:
Fill the pillar holes with epoxy.
Coat the pillars generously with epoxy and insert them into the stock.
Applying Epoxy to the Stock:
Spread a thick layer over the entire bedding area, ensuring the recoil lug recess is filled.
Large medical syringes can be used or a plastic bag with the corner cut similar to a cake decorating bag makes for an efficient and cleaner way to apply the bedding compound.
Seating the Action:
Place the barreled action into the stock.
Install the trigger guard and action screws or you can also used inletting screws with a tapered end where the screw head would be to keep the pillars centered in the pillars.
Tighten screws lightly until the action contacts the pillars, then back off slightly to prevent inducing stress.
Alignment and Support:
Verify receiver height and that the receiver is parallel to the top of the stock before the epoxy sets.
Use tape around the barrel to center it in the barrel channel (.020" clearance on the sides, .060" on the bottom).
Curing Position:
Position the rifle upright, supporting it as it would be when fired.
Allow it to cure undisturbed for at least 24 hours. This ensures the bedding conforms to the natural flex of the action under the barrel's weight.
Finalizing the Bedding
Cleanup:
Remove excess epoxy from the magazine well, chamber, and bolt lug areas before it fully cures. Cotton swabs are invaluable at this point. Depending on the epoxy you used you can use vinegar, acetone, or another product to remove epoxies from areas on you firearm. Just make sure it will not damage finishes on the firearm.
Disassembly:
After curing, carefully remove the action from the stock. You may have to give the bottom of the barrel a pop on your work bench to break it free.
Degrease and clean all bedding surfaces to eliminate release agent residue.
Files work for removing epoxy from the top of the stock where it meets the action. They also work on the inside of the stock as well. We put a slight taper on the lug areas with a file. Chisels can also be used. Be careful of chipping large pieces off than you want when removing epoxy. If you have access to a mill this will make the job easier and look better as well.
Stress Measurement:
Reassemble the rifle and perform stress tests using a dial indicator.
Aim for bedding stress less than .001"- .002” for optimal performance.
Enhancing the Bedding: Competition Pillar Bedding
For those seeking the pinnacle of bedding perfection, a secondary bedding process can further eliminate microscopic gaps caused by epoxy shrinkage (approximately 0.1%). This method involves:
Second Bedding Application:
Apply a thin layer of a low-viscosity epoxy (e.g., Brownells Steel-Bed or Devcon F-2 Liquid Aluminum) over the existing bedding.
Use a thin release agent to ensure a tight fit.
Benefits:
Eliminates any residual looseness.
Provides a near "glue-in" level of rigidity while allowing action removal.
Enhances consistency in barrel vibrations, leading to improved accuracy.
Action-Specific Bedding Considerations
Savage Actions
Rear Action Screw Issue: The factory pillar often lacks support on the back half, leading to action bending when tightened.
Solution:
Fabricate a custom pillar with full contact around the screw.
Modify the sear for clearance if necessary.
Bed the action full-length to distribute stress evenly.
Sako Actions
Separate Recoil Lug: Utilizes a lug that fits over a boss on the action.
Solution:
Use a custom recoil lug for custom builds.
Bed the lug solidly into the stock, allowing the action to seat firmly.
Ruger Actions
Angled Front Screw: Can be challenging due to its non-standard alignment.
Solution:
Install a short front pillar at the correct angle.
Proceed with bedding as usual.
Winchester and Mauser Actions
Secondary Recoil Lug Issue: Bedding vertical surfaces at the center or rear can create unintended recoil points.
Solution:
Leave clearance in these areas during bedding.
Ensure the primary recoil lug remains the sole point of recoil absorption.
Practical Tips and Common Pitfalls
Mixing Epoxy
Thorough Mixing: Inadequate mixing can lead to incomplete curing.
Tip: Mix until uniform, then mix a bit longer to be certain.
Release Agent Application
Avoiding Bonding: Failure to apply release agent properly can result in the action bonding to the stock.
Tip: Apply a thin, even layer over all potential contact areas.
Maintaining Action Alignment
Feeding and Receiver Height: Verify these before the epoxy sets to prevent functional issues.
Barrel Centering: Use tape to center the barrel in the channel during curing.
The Analogy of the Guitar String
Think of the rifle barrel as a guitar string. For the instrument to produce the same note consistently, the string must vibrate the same way each time. Similarly, for a rifle to achieve top accuracy, the barrel must exhibit consistent vibration patterns with every shot. Proper pillar bedding ensures that the action and barrel form a rigid, unified structure, minimizing unwanted movement and harmonics variation.
Conclusion
Achieving top rifle accuracy through pillar bedding is both an art and a science. It demands meticulous attention to detail, a deep understanding of rifle mechanics, and a commitment to precision at every step. By following the methods outlined in this guide, you can ensure that your bedding jobs not only meet but exceed the highest standards of craftsmanship.
Remember, the goal is to create a stress-free, rigid union between the action and stock, allowing the barrel to perform with consistent harmonics. When executed correctly, pillar bedding can unlock a rifle's true potential, delivering the exceptional accuracy that master gunsmiths and discerning shooters strive for.
About Redleg Company
At Redleg Company, we pride ourselves on our dedication to precision and performance. We craft our own aluminum pillars and utilize the finest epoxies, such as Accra-Glas and Marine-Tex, to deliver bedding jobs with stress measurements less than .001". Our commitment to excellence ensures that every rifle we work on achieves the highest level of accuracy possible.
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