Understanding the Cartridge’s Legacy
Origins and Development
The 5.45x39mm cartridge traces its roots back to the Cold War, born from the need for a smaller, more efficient round to replace the heavier 7.62x39mm used in the AK-47. The Soviet Union developed the 5.45x39mm, intending it for use in the AK-74, a rifle designed to capitalize on the round’s inherent characteristics. This cartridge offered several advantages over its predecessor, including a flatter trajectory, higher muzzle velocity, and the potential for improved accuracy. The 5.45x39mm quickly became the standard ammunition for the Soviet military and, subsequently, for many Eastern Bloc nations. Its impact extended beyond military applications, making its way into civilian markets and finding a home within the AR-15 platform.
Ballistics and Performance
The cartridge is characterized by its relatively light weight and sleek design. It typically employs bullets of varying weights, commonly in the range of sixty grains. The shape of the bullet, often featuring a distinct air pocket within its design, has contributed to discussions about its terminal ballistics. Though these features are not unique to the 5.45x39mm, they contribute to its reputation for potentially tumbling upon impact, leading to increased wound channels. It’s crucial to emphasize that these characteristics are subject to ongoing debate and are influenced by a multitude of factors, including bullet type and impact angle.
Availability and Cost
The availability and cost of 5.45x39mm ammunition can fluctuate depending on the region and current geopolitical factors. While it may have historically been more affordable than some other popular rounds, such as 5.56 NATO, prices are subject to market forces. Ammunition quality also varies, so it is important to research your ammunition and choose from reputable brands. The relative affordability of the cartridge, when it’s available, can be a significant draw for shooters looking to maximize their time at the range without breaking the bank.
Why Choose a 5.45×39 Barrel for Your AR-15?
Cost-Effectiveness
One of the most compelling reasons to consider a **5.45×39 AR barrel** is its potential for cost savings. Ammunition costs are a significant factor for any shooter. This cartridge can sometimes be found for a lower price than its NATO counterpart, which allows for extended training sessions and more opportunities to hone your skills. Furthermore, if you’re seeking to build an AR-15 that stands out from the crowd, the 5.45x39mm presents a unique opportunity. It’s a less common caliber within the AR-15 world, making your rifle a conversation piece and a statement of your interest in exploring alternative chamberings.
Unique Shooting Experience
Beyond the financial advantages, the 5.45x39mm offers a distinct shooting experience. While individual experiences vary, some shooters find that the cartridge has a unique recoil impulse that’s often described as softer than 5.56 NATO. The muzzle blast and overall handling may also differ, contributing to a more enjoyable shooting session for some.
Essential Factors When Selecting Your Barrel
Barrel Material and Construction
Choosing a **5.45×39 AR barrel** is a critical step in building a reliable and accurate AR-15. Several factors deserve careful consideration.
The material the barrel is made of is essential. Options often include chrome moly steel and stainless steel. Chrome moly steel provides a balance of durability and affordability, making it a popular choice for many. Stainless steel generally offers increased corrosion resistance and potential for improved accuracy, often at a higher price point. The choice of material often depends on your intended use and the environmental conditions where you’ll be shooting.
Barrel Profile
The barrel profile, referring to the barrel’s external shape, can also impact performance and handling. Common profiles include government profile, which maintains a more slender barrel ahead of the front sight post; and heavy profiles, which offer increased weight and rigidity, potentially enhancing accuracy. Selecting the appropriate profile hinges on your priorities – do you want a lightweight, maneuverable rifle or one optimized for long-range accuracy?
Rifling Twist Rate
The rifling twist rate, the rate at which the rifling grooves spin the bullet, is vital for optimal accuracy. The twist rate directly impacts the stability of the bullet in flight. 5.45x39mm barrels often have a twist rate designed to stabilize the commonly used bullet weights of the cartridge. Make sure you choose a barrel that suits the bullet weights you intend to use. Using the wrong twist rate can lead to accuracy issues. For most 5.45×39 ammunition, a 1:8 or 1:9 twist rate is typical.
Compatibility with AR-15 Components
Ensure the barrel is compatible with your AR-15 upper receiver. AR-15 barrels are designed to interface with the upper receiver through a threaded connection. You can check the compatibility of the barrel by confirming the threads are correct. This compatibility is critical, and ensure the barrel meets all dimensions to secure fit.
5.45x39mm Bolt Compatibility
For reliable functioning, you’ll need a bolt designed specifically for the 5.45x39mm cartridge. The bolt face is machined to accommodate the rim of the cartridge, and the extractor is designed to effectively grasp and extract the spent casings. This is important to ensure extraction.
Barrel Length Considerations
The overall barrel length has a significant impact on ballistics, maneuverability, and overall weight. A shorter barrel results in greater maneuverability, suitable for close-quarters combat. Longer barrels will offer a higher muzzle velocity and potentially improved long-range accuracy. Common barrel lengths range from the standard carbine-length to longer models for dedicated precision shooting. The optimal barrel length depends on your intended use and the desired balance between different factors.
Manufacturer Reputation
Choose barrels from reputable manufacturers. Look for brands with a track record of producing high-quality AR-15 components. Research customer reviews and seek input from experienced shooters to get insights into the barrel’s performance, durability, and customer service.
Installation and Assembly Made Easier
Tools Required
Installing a **5.45×39 AR barrel** requires a few specialized tools and some patience. This task usually involves the use of a barrel nut wrench, a torque wrench, and a set of gunsmithing punches.
Step-by-Step Installation Guide
Before proceeding, always ensure that the firearm is unloaded and that you have taken all safety precautions. Disassemble the upper receiver from the lower receiver. Remove the handguard and other accessories. Use the appropriate tools to unscrew and remove the old barrel nut and barrel.
Carefully slide the new **5.45×39 AR barrel** into the upper receiver, ensuring it aligns correctly with the gas port. Install the barrel nut and tighten it to the manufacturer’s recommended torque specifications, using a torque wrench. Proper torque is critical for ensuring a secure fit and maintaining accuracy.
Headspacing Procedures
After installing the barrel, you’ll need to verify the headspace. Headspace is the distance between the bolt face and the point in the chamber where the cartridge stops. Ensuring proper headspace is paramount for safety and reliable functioning. Use headspace gauges to test the barrel after installation.
Common Challenges and How to Address Them
Failure to Feed/Eject
Even with careful selection and proper installation, some issues may arise with your 5.45×39 AR build.
Failure to feed or eject can be caused by several factors. The magazine can be at fault, causing the rounds not to be pushed up into the chamber. It might be caused by the bolt not properly picking up a round from the magazine. In some cases, the gas system may be improperly aligned or malfunctioning. Examine your rifle closely, and address each of these potential issues. Replace the bolt or magazine if necessary. Make sure the gas system is properly aligned.
Accuracy Problems
Accuracy problems can often be traced to a few common culprits. Loose components, a faulty optic, or improper barrel installation are just some of them. Thoroughly inspect your rifle. The bullet weight and twist rate might not be compatible. Ensure that all screws are properly tightened, and the optic is securely mounted. If the issue persists, you may need to seek professional help from a gunsmith to diagnose and resolve the problem.
Compatibility Issues
Many have reported compatibility problems. Be sure to use magazines and bolts designed specifically for 5.45×39. These may look the same as those for 5.56, but dimensions are different.
Maintaining and Caring for Your Barrel
Cleaning Procedures
Proper maintenance will extend the life of your **5.45×39 AR barrel** and ensure it functions reliably.
Clean your barrel regularly after each shooting session. Use a quality bore cleaner, a cleaning rod, and appropriate brushes to remove carbon buildup and residue. Follow the manufacturer’s instructions for cleaning your barrel.
Lubrication
Lubrication is essential for smooth operation. Apply a light coat of gun oil to the moving parts of the bolt carrier group. Ensure the bolt itself is properly lubricated for smooth cycling.
Storage
Store your AR-15 in a clean, dry place. Keep the firearm away from extreme temperatures and humidity, which can damage the components. Ensure the firearm is unloaded before storing it.
In Conclusion: Embracing the 5.45×39 AR Experience
The **5.45×39 AR barrel** provides a distinct and potentially cost-effective way to enjoy the AR-15 platform. By carefully considering the factors outlined above and making informed choices, you can build a reliable and accurate rifle tailored to your shooting needs. While the 5.45x39mm cartridge might not be as common as 5.56 NATO, its unique characteristics and the potential for cost savings make it a compelling option for many shooters. With proper selection, installation, and maintenance, you can enjoy the advantages of this versatile round and experience the AR-15 in a new and exciting way.
Where to Find Information and Resources
When building your 5.45×39 AR-15, it is important to be aware of resources. This may include online communities, professional gunsmiths, and other firearm experts. Be sure to consult resources to help you with your build.
