Understanding the Components: The Key Players
The Buffer Tube’s Role
The buffer tube, also known as the receiver extension, is a critical component that houses the buffer and spring assembly. This assembly performs a crucial function: it manages the recoil impulse generated when the rifle fires. The buffer absorbs the energy of the bolt carrier group as it moves rearward, preventing excessive jarring and contributing to the overall smooth operation of the firearm. The design and dimensions of the buffer tube significantly impact the reliability and lifespan of the AR15.
The Stock’s Role
The stock serves as the primary point of contact between the shooter and the rifle. Its purpose is to provide a comfortable and stable platform for shouldering the weapon, allowing for accurate shot placement and comfortable handling. Stocks are available in a wide variety of designs, from fixed, solid platforms to adjustable models that permit tailoring the length of pull (LOP) to the shooter’s individual body size. The proper stock configuration directly influences the shooter’s ability to acquire the target quickly and maintain a consistent cheek weld. Choosing the right stock is, therefore, of utmost importance for both performance and overall comfort.
The Critical Relationship
The success of the relationship between the stock and buffer tube hinges on their compatible interaction. The buffer tube acts as the structural anchor, providing a stable platform for the stock to attach to. The stock slides onto the buffer tube, and depending on its design, it may be fixed in place or adjustable along the tube. The connection must be secure and fit snugly without excessive play or binding. A properly fitted stock is vital for comfortable shooting and the rifle’s overall balance. Any looseness or incompatibility can lead to inaccurate shooting, discomfort, and even mechanical issues.
The Common Causes of AR15 Stock Incompatibility
Commercial-Spec vs. Mil-Spec Confusion
A frequent source of trouble is the distinction between what are known as commercial-spec and mil-spec buffer tubes. The mil-spec standard, initially developed for military use, has become the standard for AR15 rifles. However, the commercial specification remains prevalent due to its accessibility and often its affordability. The critical difference lies in the outer diameter of the buffer tube. Mil-spec tubes have a slightly smaller outer diameter than commercial-spec tubes. The result is that stocks designed for one type of tube will not fit properly onto the other. The stock will either be too loose, resulting in instability, or too tight, making installation or adjustment extremely difficult, if not impossible. The failure to identify the correct specification is one of the most typical causes of this frustration.
Defective or Mis-machined Components
Another source of this issue could be defects within components. Manufacturing issues can plague a variety of components. The stock may not have been properly machined to the correct dimensions. The buffer tube might have irregularities from the manufacturing process. Defective components often lead to an inability to properly mount a stock onto the buffer tube. This results in a faulty fit, loose or non-functional adjustments, and a frustrating build. The manufacturing process demands high standards to guarantee the proper functionality of the rifle, highlighting the significance of choosing reputable brands.
Incorrect Assembly
Incorrect assembly can contribute to this problem. While seemingly straightforward, installing a buffer tube and subsequently the stock involves a series of procedures, from threading the buffer tube into the receiver to properly aligning all the components. Mishaps during the installation process can lead to interference. Over-tightening, cross-threading, or not tightening the castle nut properly will create problems. These missteps can compromise the integrity of the buffer tube or the fit of the stock.
Aftermarket Compatibility Issues
The extensive aftermarket for AR15 components presents both advantages and potential drawbacks. The flexibility allows for a large range of options, but the compatibility of parts from different manufacturers will always pose a challenge. Some stocks will not fit with certain buffer tubes, even when both are marketed as matching specifications. Variations in manufacturing tolerances can result in components that are technically within specification but still do not fit together as intended. Before a purchase, it is advisable to research and consult product descriptions to ensure that the stock is intended for the same tube, as well as verify that the two have been designed for each other.
Damage
Damage to any part of the system can lead to a failure of fit. The receiver extension may be dented or bent, making it unable to accommodate a new stock. The stock itself might have been cracked or warped from rough handling. These issues will cause the stock to not fit properly, and often, the stock will not fit at all. Always visually inspect components for any damage before assembling them.
Troubleshooting and Solutions: Bringing the Rifle Together
Visual Inspection and Measurement
Begin by carefully examining both the buffer tube and the stock for any obvious damage. Inspect for cracks, dents, or any other visible signs of wear or damage. Check the stock’s mounting mechanism. Measure the outside diameter of the buffer tube using calipers. The reading is the single most reliable way to verify the buffer tube specification. Compare the measurement to known specifications. For example, a mil-spec buffer tube will typically measure around 1.148 inches (29.16 mm), while a commercial-spec tube measures approximately 1.168 inches (29.67 mm). A discrepancy between the measurements and published specifications can indicate that the parts are out of spec.
Identifying the Tube Specification
Confirming the buffer tube type is often the critical step. Unfortunately, buffer tubes rarely come with markings indicating whether they are mil-spec or commercial. Without markings, determine the specification using alternative tactics. If you have access to other stocks known to fit mil-spec or commercial tubes, try them to see if the fit is improved. If a mil-spec stock fits the tube, then the buffer tube is mil-spec. If a commercial stock fits, the tube is commercial.
Trying Alternative Solutions
Sometimes, the problem is not major, and a simple adjustment can be sufficient. If the stock is too loose on the buffer tube, try wrapping the buffer tube with a thin layer of tape. This will help tighten the fit. Note that this method is a temporary fix that may not be ideal. A more permanent solution might be needed. If the stock is too tight, very carefully consider the method of sanding the stock to improve fit. Sanding should be done in small increments, and you must test the fit frequently to avoid removing too much material. Sanding is risky and can make a poor fit worse.
Seeking Professional Help
Sometimes, the best approach is to consult a professional. If you are experiencing difficulties, it is highly recommended to consult a gunsmith. A gunsmith has the expertise and equipment necessary to properly diagnose and resolve the problem. They can inspect the parts, identify manufacturing issues, and provide effective solutions. The gunsmith’s assessment will often determine if the parts need replacing.
Replacing the Parts
Ultimately, if the buffer tube and stock are incompatible, replacing the offending parts is often the most efficient solution. When purchasing replacements, make sure to choose components that match the appropriate specification. If your stock is for a commercial tube, purchase a commercial tube. If your stock is for a mil-spec tube, purchase a mil-spec tube. When looking for replacements, investigate manufacturers that are known for quality. Well-known brands use high-quality materials and adhere to strict quality control.
Prevention: Steps to Take to Prevent Future Problems
Researching Components Before Purchasing
Prior to purchasing components, conduct thorough research. Read reviews from other users, and review the manufacturer’s specifications. Verify the compatibility before making any purchases. This research can save a great deal of time and frustration. Determine the specification required for your build before placing your order. Ensure that both stock and buffer tube are compatible with each other.
Buying from Reputable Manufacturers
Make sure to purchase components from well-known and trustworthy manufacturers. Reputable manufacturers use high-quality materials. They also exercise tight quality control procedures. Choosing reputable brands will help guarantee that the components are made correctly and perform as designed.
Proper Installation Procedures
Install components properly. Follow all manufacturer’s guidelines. When installing the buffer tube, do not over-tighten any of the fasteners. A slight over-tightening will compromise the function. Using the right tools will help assure a correct assembly. By adhering to this instruction, you can increase the likelihood of the components working as intended.
Conclusion: Final Thoughts on a Smooth Build
The incompatibility of an AR15 stock with its buffer tube can be a source of great frustration for anyone building or modifying this popular platform. The good news is that the reasons for incompatibility are frequently traceable to the specifications of the components. By understanding the key players, being aware of the common culprits, and following the troubleshooting steps described, you can often identify the problem and implement effective solutions.
By selecting the correct components, paying close attention to the fit, and adhering to proper assembly procedures, you can build or upgrade an AR15 that provides reliable function and consistent performance.
If you have a rifle with components that do not fit together, take the steps outlined above, and if you are not sure, seek professional guidance. Do not be discouraged. The AR15 is a great platform, and by focusing on the details, you can achieve the desired outcome. Be sure to check your build and take action when necessary to make sure your rifle fits you properly. By doing so, your shooting experience will be vastly improved.
