Mastering Ammunition Precision: An In-Depth Guide to the Hornady 390750 Primer Case Reamer

For the dedicated reloader, precision is paramount. Every component, every step in the ammunition preparation process, contributes to the final accuracy and reliability of the cartridge. Among the most critical yet often overlooked steps is primer pocket preparation. This is where tools like the Hornady 390750 Primer Case Reamer become indispensable. If you've ever wondered how to achieve more consistent primer seating, eliminate issues caused by crimped brass, or simply elevate your handloading game, this comprehensive guide is designed for you.

Why Primer Pocket Preparation is Crucial for Reloading Excellence

Imagine two identical cartridges, but one has a perfectly uniform primer pocket, and the other has an uneven or crimped one. Which one do you think will perform better? The answer lies in consistency. The primer, though small, is the igniter of the entire firing sequence. For optimal performance, it needs to be seated uniformly, securely, and at the correct depth.

What problems does improper primer pocket preparation cause?

• Inconsistent Primer Seating: If the primer pocket is dirty, uneven, or has a crimp, the primer may not seat fully or consistently. This can lead to a host of problems, from misfires to variations in ignition time.
• Reduced Accuracy: Variations in primer ignition translate directly to variations in muzzle velocity, which in turn leads to wider shot groups and reduced accuracy. For competitive shooters or precision enthusiasts, this can mean the difference between winning and losing.
• Primer Failure or Damage: Forcing a primer into a crimped or undersized pocket can deform the primer cup, potentially causing a malfunction or even a dangerous situation.
• Shortened Brass Life: Repeatedly forcing primers into inadequate pockets can stress the brass, leading to cracks around the primer pocket and premature case failure.

This is precisely the challenge the Hornady 390750 Primer Case Reamer addresses. It’s not just a tool; it’s an investment in the quality, safety, and consistency of your handloaded ammunition.

Understanding the Hornady 390750 Primer Case Reamer

The Hornady 390750 Primer Case Reamer is specifically designed as an extra reamer head for Hornady's Primer Pocket Reamer system. This means it's an accessory that attaches to a universal handle (sold separately, typically as part of a larger kit or available individually) to allow you to precisely prepare primer pockets. While the term "Universal" might appear in some descriptions, it's crucial to understand that this specific reamer, indicated by its "Small" series designation (as per the product specifications), is optimized for small primer pockets. This includes common calibers such as .223 Remington, .308 Winchester (some variants), 9mm Luger, and many others that utilize small rifle or small pistol primers.

Who is this tool for?

• Reloaders Using Military or Once-Fired Brass: Military brass often features a crimped primer pocket to secure the primer more firmly during combat conditions. This crimp must be removed before a new primer can be seated. The Hornady 390750 is ideal for this task.
• Precision Shooters: Those chasing sub-MOA groups know that every variable counts. Uniforming primer pockets ensures consistent ignition, which is a cornerstone of precision.
• High-Volume Reloaders: While other methods exist, reaming offers a quick and effective way to process large quantities of brass, especially if you prioritize a clean, chamfered pocket over mere crimp removal.
• Anyone Experiencing Inconsistent Primer Seating: If you find primers difficult to seat, or if they don't sit flush, a primer pocket reamer is often the solution.

Key Features and Benefits

The Hornady 390750 Primer Case Reamer is a testament to Hornady's reputation for producing high-quality reloading equipment. Crafted from durable steel, this reamer head is built to withstand rigorous use and provide consistent results over thousands of cases.

Core Features:

• Material Excellence: Constructed from robust steel, ensuring long-term durability and resistance to wear, even when processing tough brass.
• Precision Engineered: Designed to accurately remove primer crimps and uniform small primer pockets, creating a consistent seating surface.
• Accessory Design: Functions as an interchangeable head for Hornady's existing primer pocket reamer tool, offering versatility and cost-effectiveness if you already own the handle.
• "Small" Primer Specific: Optimized for all small rifle and small pistol primer pockets, making it indispensable for many popular calibers.

Benefits to the Reloader:

• Enhanced Primer Seating Consistency: Creates a uniform pocket, allowing primers to seat smoothly, consistently, and at the correct depth every time. This is critical for reliable ignition.
• Improved Ignition Reliability: A consistent seating depth ensures the primer anvil is properly crushed, leading to a more reliable and uniform flash, directly impacting powder ignition.
• Superior Accuracy: By standardizing the primer pocket, you eliminate a variable that can lead to velocity variations, contributing to tighter groups downrange. Many precision shooters consider this step non-negotiable for competitive accuracy.
• Extended Case Life: Proper reaming reduces stress on the primer pocket during seating, helping to prevent cracks and extending the usable life of your valuable brass.
• Effortless Crimp Removal: Quickly and efficiently removes military crimps, transforming once-fired military brass into reusable components.
• Safety Assurance: By preventing improper primer seating, the reamer contributes to safer reloading practices, minimizing the risk of primer damage or unexpected ignition issues.
• Time Efficiency: While it adds a step, the efficiency of the tool itself, especially when paired with a powered reaming system or a comfortable handle, makes the process surprisingly quick for preparing batches of brass.

How to Use the Hornady 390750 Primer Case Reamer: A Step-by-Step Guide

Using the Hornady 390750 Primer Case Reamer is straightforward, but precision and attention to detail are key.

1. Preparation:
   • Clean Your Brass: Ensure your brass is cleaned (e.g., tumbled) and decapped. This provides a clear primer pocket and prevents abrasive grit from damaging the reamer.
   • Attach the Reamer Head: Securely screw the Hornady 390750 Primer Case Reamer head onto your Hornady Primer Pocket Reamer handle or a compatible power tool adapter. Ensure it's snugly tightened to prevent wobble.
2. The Reaming Process (Manual Method):
   • Hold the Case Securely: Grip the brass case firmly in one hand. For best results and consistency, consider using a universal shell holder or a case holder that fits your specific caliber, providing a stable platform.
   • Insert the Reamer: Carefully insert the tip of the reamer into the primer pocket.
   • Apply Gentle Pressure and Twist: Apply gentle, steady pressure and twist the handle. The sharp edges of the reamer will shave away the crimp or irregularities.
   • Feel for Resistance Change: You will feel initial resistance if there’s a crimp. As the crimp is removed and the pocket is uniformed, the resistance will lessen, and the reamer will turn more smoothly. Do not over-ream; the goal is just to clean up the pocket and remove the crimp, not to enlarge the pocket excessively. A quick turn or two is usually sufficient.
   • Inspect the Pocket: Remove the reamer and visually inspect the primer pocket. It should appear clean, free of crimp marks, and slightly chamfered at the edge. A new primer should seat with consistent, firm pressure, but without excessive force.
3. The Reaming Process (Powered Method - if applicable):
   • If using a power case prep center (like the Hornady Lock-N-Load Case Prep Trio), simply insert the 390750 reamer into the appropriate station.
   • Hold the brass case firmly and guide the primer pocket onto the spinning reamer head.
   • Apply light pressure until the crimp is removed and the pocket is clean. The consistent RPM of a powered tool often provides very uniform results with minimal effort.
4. Cleaning Up: After reaming, it's good practice to briefly tumble or wipe down the brass to remove any small shavings or debris from the primer pocket. This ensures a perfectly clean pocket for primer seating.

Reaming vs. Swaging: When to Choose What

While both reaming and swaging are effective methods for dealing with crimped primer pockets, they achieve the result in different ways and have distinct advantages.

Reaming (Hornady 390750): This method cuts away material from the primer pocket. It removes the crimp by chamfering the inner edge of the primer pocket, effectively creating a slight bevel that allows the new primer to pass easily.

• Pros: Leaves a clean, chamfered edge; can also clean up rough or uneven pockets; works well on brass with heavily formed crimps.
• Cons: Removes a tiny amount of brass material; can be slower for very high volume if done manually; requires careful technique to avoid over-reaming.

Swaging: This method reforms the primer pocket by pushing the crimped material back into place, without removing any brass.

• Pros: No material is removed; can be very fast for high-volume processing, especially with dedicated swaging tools.
• Cons: Does not clean up rough pockets; may not be as effective on very heavy crimps; can sometimes work-harden the brass around the pocket.

For many reloaders, particularly those who prioritize precision and a perfectly clean pocket for optimum primer seating, reaming with a tool like the Hornady 390750 is the preferred method. It offers a level of pocket uniforming that swaging typically doesn't, contributing to that extra degree of consistency.

Maintaining Your Hornady Primer Case Reamer

To ensure the longevity and continued effectiveness of your Hornady 390750 Primer Case Reamer, simple maintenance is key:

• Clean After Use: After each reloading session, use a stiff brush to remove any brass shavings or carbon buildup from the reamer head. A little gun cleaner or solvent can also be applied and then wiped dry.
• Lubrication (Optional but Recommended): A very light coat of rust preventative oil can be applied to the steel surfaces if storing for an extended period, especially in humid environments, to prevent corrosion.
• Proper Storage: Store the reamer in a clean, dry place, ideally in its original packaging or a dedicated compartment in your reloading toolbox to protect the cutting edges from damage.
• Avoid Excessive Force: Let the reamer do the work. Excessive force can dull the cutting edges prematurely.

The Hornady Advantage: A Legacy of Precision

Hornady has been a trusted name in the shooting and reloading industry for decades, known for its commitment to innovation, quality, and precision. When you choose the Hornady 390750 Primer Case Reamer, you're not just buying a tool; you're investing in a piece of equipment backed by a legacy of excellence.

Hornady understands the demands of modern reloaders, from hobbyists to competitive professionals. Their tools are designed to integrate seamlessly into a complete reloading workflow, ensuring that every step, from case cleaning to bullet seating, contributes to the highest possible standard of ammunition. The reliability and durability of Hornady products mean you can focus on the art and science of reloading, rather than worrying about your tools.

For those seeking to maximize their ammunition's performance, whether for target shooting, hunting, or competition, the attention to detail provided by tools like the Hornady 390750 Primer Case Reamer is invaluable. It helps answer the critical question: "How do I make my handloads as accurate and reliable as possible?" The answer, in part, lies in meticulous preparation, starting with the primer pocket. You can find this essential Hornady reloading accessory, along with a wide range of other high-quality reloading supplies, at DEGuns.com. Elevate your reloading process and unlock the true potential of your ammunition with Hornady.

Specification	Detail	Benefit
Brand	Hornady	Trusted name in reloading equipment
Series	Small	Optimized for common small primer pockets
Model	Primer Reamer	Dedicated tool for primer pocket preparation
Color	Silver	Standard, clean finish
Function	Case Reamer	Precisely removes crimps and uniforms pockets
Material	Steel	Durable, long-lasting performance
SKU	23195	Unique inventory identifier
UPC	090255907506	Universal Product Code for easy identification
MPN	390750	Manufacturer Part Number for exact match