Disclaimer:
The information provided in this blog post is intended for educational purposes only and should not be construed as professional advice or instruction. Modifying or working on firearms, including chambering processes, requires specialized skills and experience. Redleg Company Inc. does not assume responsibility or liability for any harm, damage, or injury resulting from the use or misuse of the methods and techniques described. Firearms modifications can affect the safety, performance, and reliability of a rifle. We strongly recommend that any chambering work be performed by a qualified and experienced gunsmith. Always adhere to proper safety protocols and consult a professional before attempting any modifications. Redleg Company Inc. disclaims all liability for any direct or indirect consequences arising from the use of this information.
At Redleg Company, we specialize in crafting precision rifles built to deliver unmatched accuracy. One of the critical steps in achieving this level of performance is the chambering process. Chambering a rifle barrel is not just about cutting a hole; it’s about ensuring every aspect of the bore, chamber, and throat alignment is perfect. In this post, we dive deep into the chambering process we use, sharing our insights and methods to help you understand what sets our rifles apart.
Understanding the Role of Chambering in Rifle Accuracy
The chambering process is crucial because it directly impacts how the bullet enters the bore and aligns with the rifling. Even a minor misalignment can cause the bullet to wobble, degrade accuracy, and impact consistency. Traditional chambering methods often leave room for these errors. After years of meticulous testing and refinements, we have developed a method that overcomes these traditional challenges, ensuring perfect alignment and maximum accuracy.
Challenges with Traditional Chambering Methods
Traditional methods like “chambering between centers” or the “dial both ends” approach have limitations:
Bore Curvature Issues: All barrels have some degree of bore curvature. When using the "dial both ends" method, where the bore is aligned at both the throat and crown ends, the curvature between these two points can cause the bore to enter the chamber at an angle. This misalignment affects how the bullet aligns with the rifling and exits the barrel, impacting accuracy.
Runout and Misalignment: Inconsistent support and alignment during the chambering process can result in measurable runout (misalignment of the bore axis with the chamber axis). This issue can cause the bullet to enter the bore at a slight angle, reducing accuracy.
Our Preferred Chambering Method for Superior Accuracy
To address these issues, we use a chambering method that focuses on aligning the short section of the bore just ahead of the throat perfectly with the chamber. Here’s a detailed breakdown of our process:
Action Preparation and Bolt Lug Fitting
Before starting the chambering process, we ensure the rifle’s action is correctly prepared to support maximum accuracy:
Bolt Lug Contact: Proper bolt lug contact is essential for benchrest-quality accuracy. We ensure all lugs have at least 50% contact with their seats in the receiver, reducing action flex and vibration during firing, which can affect accuracy.
Bolt Play Reduction: We reduce bolt play by sleeving the original bolt to enlarge its diameter or by applying a thin layer of epoxy inside the bolt bore raceway. This step minimizes unwanted bolt movement, enhancing consistency and accuracy.
Ensuring Smooth Operation: We make sure the firing pin and all bolt parts operate smoothly without any binding. This includes checking for proper firing pin travel and spring tension to ensure reliable ignition. Even small issues in these areas can affect the rifle's performance.
Lathe Setup and Initial Bore Alignment
The first step involves setting up the barrel in the lathe. We use a modified "through-the-headstock" method:
Barrel Support: The chamber end of the barrel is supported in a 4-jaw chuck, while the opposite end is supported by a "spider" with four opposing screws on the outboard end of the headstock spindle. This setup allows us to make precise adjustments to align the bore.
Shimming for Precision: To ensure the barrel pivots correctly during alignment, we use small L-shaped aluminum shims between the chuck jaws and the barrel. This setup allows for fine adjustments and prevents the barrel from slipping, maintaining alignment accuracy.
Precision Dialing-In Process
The key to our method is precise dialing-in of the bore section just ahead of the throat:
Indicator Setup: We use a Mitotoyu .0001" dial test indicator with a 1.5" long tip to measure runout directly in the bore grooves. This indicator is extremely sensitive and allows us to detect even the slightest misalignment.
Bore Alignment: We start by aligning the bore within .001" at the chamber end and pre-drill the chamber. Then, we fine-tune the alignment, adjusting the bore to run true to within .0001" to .0002". This precision ensures the bore is perfectly aligned with the chamber, eliminating any angle that could affect bullet trajectory.
Chamber Boring and Reaming
After achieving perfect bore alignment, the next step is boring and reaming the chamber:
Boring the Chamber: Using a small boring bar, we machine the chamber hole true, aligning it dead-center to the bore. This step ensures that when the chamber reamer is used, it follows the trued hole perfectly, maintaining the alignment from the chamber to the bore.
Reaming the Chamber: The chamber reamer is carefully fed into the bored hole, ensuring it aligns perfectly with the bore ahead of the chamber. We use slower RPMs (300 to 500)and a slow feed rate initially to avoid reamer chatter, which can cause imperfections in the chamber.
Measuring and Minimizing Reamer Chatter: During the chamber-cutting process, we constantly monitor the depth and quality of the chamber to detect any signs of reamer chatter. To measure chatter, we use a dial test indicator, which provides precise readings of any surface irregularities. To prevent chatter, we employ a technique where wax paper or a slit patch is placed over the reamer nose. This method effectively dampens vibrations, ensuring a smooth, chatter-free finish. Additionally, we use headspace and feeler gauges to accurately measure the chamber’s depth, guaranteeing that it meets the exact specifications required for optimal performance.
Final Chamber and Bore Inspections
Precision is crucial throughout the chambering process. After reaming, we perform several inspections to ensure everything is perfectly aligned:
Borescope Inspection: We use a borescope to inspect the chamber and throat for any imperfections, such as burrs or rough spots. Even a small burr can affect accuracy by tearing the bullet jacket as it enters the bore.
Runout Measurement: Using a .0001" long-reach dial test indicator, we check the runout throughout the chamber, neck, and freebore. We aim for zero or near-zero runout, indicating perfect alignment.
Headspace Setting and Final Adjustments
Proper headspace is crucial for safe and accurate firing:
Headspace Measurement: We use Go and No-Go gauges to set the headspace. Our goal is to achieve a minimum headspace of .0005" to .0025", depending on the type of action (custom or factory). This precise headspace ensures the bullet is properly seated in the chamber, reducing the risk of excessive pressure or misfires.
Final Alignment Check: After setting the headspace, we double-check the chamber and bore alignment to ensure everything remains perfectly true. Any deviation can be corrected with slight adjustments, maintaining the precision needed for extreme accuracy.
Throat Cutting and Crown Finishing
The final steps involve customizing the throat and cutting the crown:
Throat Customization: Depending on the customer’s needs, we may cut a larger diameter neck or a longer throat. We use separate neck and throating reamers to achieve the desired dimensions, providing flexibility to meet various customer requirements.
Crown Cutting: The crown is cut while ensuring the last 1.5" to 2" of the bore is aligned perfectly straight and true. A precise crown is crucial for accuracy, as it ensures the bullet exits the barrel evenly, preventing gas blow-by that could affect trajectory.
Final Polishing and Quality Checks
After chambering and fitting the barrel:
Polishing: We lightly polish the chamber and radius the chamber mouth to ensure smooth feeding and ejection of cartridges.
Final Quality Checks: Every rifle undergoes rigorous final checks to ensure all components operate smoothly and meet our accuracy standards. This includes verifying the smooth operation of the firing pin and ensuring there is sufficient firing pin travel and spring tension for reliable ignition.
Why Our Method Delivers Superior Accuracy
By focusing on the critical alignment of the bore just ahead of the throat with the chamber, we eliminate the common issues found in traditional chambering methods. Our process ensures that the bullet enters the bore perfectly straight, minimizing any potential for accuracy loss. The result is a rifle capable of delivering exceptional accuracy, whether it’s for long-range benchrest, tactical, or hunting applications.
Conclusion
At Redleg Company, our commitment to quality and precision is evident in every rifle we build. Our advanced chambering process is just one example of the meticulous care and attention to detail that goes into crafting a rifle that performs at the highest level. If you’re looking for a rifle that delivers extreme accuracy shot after shot, we’re here to help.
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