The Art and Science of Bullet Sizing: Achieving Precision for Reloaders

For any serious reloader, especially those who venture into the rewarding world of casting their own bullets, understanding and implementing proper bullet sizing is an absolutely critical step. It’s not merely an option; it's a fundamental process that ensures your handloads achieve optimal performance, accuracy, and safe operation. Whether you're a seasoned handloader or just beginning your journey into producing custom ammunition, mastering bullet sizing is key to unlocking the full potential of your firearms.

So, what exactly is bullet sizing, and why is it so important? In essence, bullet sizing is the process of uniformly reducing the diameter of a cast bullet to a specific, precise dimension. This is particularly vital for cast lead bullets because they often come out of the mold slightly oversized or with minor inconsistencies. Unlike factory-produced jacketed bullets, which are typically held to very tight tolerances, cast bullets vary based on the mold, the alloy used, and even the casting temperature. These variations, if not addressed, can lead to a host of problems including poor accuracy, excessive lead fouling in the barrel, difficult chambering, and unreliable feeding.

The primary problem that bullet sizing solves is inconsistency. An undersized bullet can "gas cut," allowing hot propellant gases to bypass the bullet in the bore, eroding the bullet and leading to severe fouling. This results in decreased velocity, poor accuracy, and a barrel that quickly becomes caked with lead, requiring laborious cleaning. Conversely, an excessively oversized bullet might be difficult or impossible to chamber, or it could generate dangerously high pressures upon firing. The goal is to achieve a consistent bullet diameter that precisely matches the bore dimensions of your firearm, specifically the groove diameter, or is just slightly larger to ensure a perfect seal and engagement with the rifling.

Properly sized bullets engage the rifling uniformly, ensuring stable flight and superior accuracy. They also prevent lead buildup, which is a common frustration for cast bullet shooters. Furthermore, many cast bullets require the application of a gas check – a small copper or aluminum cup that fits over the base of the bullet. Gas checks protect the bullet base from the hot gasses, preventing deformation and further reducing lead fouling at higher velocities. Bullet sizing dies are often designed to facilitate the seamless application and crimping of these gas checks.

Introducing the Lee Precision Lube & Size Kit (Model 90037): Your Gateway to Consistent Performance

For reloaders seeking a straightforward, effective, and reliable solution for sizing and lubricating cast bullets, the Lee Precision Lube & Size Kit (Model 90037) stands out as an exceptional choice. Engineered with the user in mind, this kit streamlines the often-overlooked yet critical step of bullet preparation, making it accessible even for those new to the intricacies of handloading. This robust steel kit is designed specifically for use with single-stage presses, offering a simple and highly efficient method to prepare your cast bullets for loading.

This kit is ideally suited for:

• Cast Bullet Enthusiasts: Anyone who casts their own lead bullets for pistol or rifle ammunition.
• Accuracy Seekers: Reloaders determined to achieve tighter groups and more consistent ballistic performance.
• Cost-Conscious Shooters: Those looking to maximize the value of their cast bullets by ensuring optimal functionality and reducing waste.
• Single-Stage Press Owners: Individuals who prefer the methodical pace and control offered by a single-stage reloading press.
• DIY Ammunition Producers: Reloaders committed to producing high-quality ammunition from scratch, ensuring every component meets their exacting standards.

The core problem this kit solves is the challenge of inconsistent cast bullet diameters. Without proper sizing, variations from the mold can lead to significant issues during firing. The Lee Precision Lube & Size Kit addresses this directly, ensuring each bullet is uniformly dimensioned, leading to improved accuracy, reduced lead fouling, and smoother feeding in your firearm's chamber. It simplifies the process of achieving consistent bullet dimensions, which is paramount for predictable and safe reloading outcomes.

Unpacking the Essentials: What's Inside the Lee Precision Lube & Size Kit?

The Lee Precision Lube & Size Kit is thoughtfully designed, comprising three essential components that work in harmony to deliver perfectly sized and prepared bullets. Each part is crafted from durable steel, ensuring longevity and reliable performance through countless sizing operations.

1. The Sizer Die: This is the heart of the kit. Constructed from robust steel, the sizer die features standard 7/8 x 14 threads, making it universally compatible with virtually any single-stage reloading press available on the market today. Its internal diameter is precision-machined to the specific size you select (e.g., .358", .452", etc.), ensuring that every bullet pushed through it conforms to the desired dimension. The smooth internal finish of the die helps to minimize friction and prevent marring of the bullet during the sizing process, contributing to a clean, consistent result.
2. The Push Through Punch: This innovative component replaces the traditional shell holder on your press's ram. Unlike conventional sizing methods that may require specific nose punches for different bullet profiles, the Lee Precision system utilizes a universal push-through punch. This means bullets are pushed through the sizing die nose-first, eliminating the need for multiple specialized nose punches and simplifying your setup considerably. The design ensures consistent pressure is applied to the bullet base, facilitating a smooth passage through the sizer die.
3. The Sizer Box (Bullet Catcher): A convenient and practical addition, the sizer box is designed to collect your newly sized bullets as they exit the die. This integrated catcher prevents bullets from scattering across your reloading bench or falling to the floor, keeping your workspace tidy and ensuring all your hard work is neatly contained and ready for the next step in the reloading process. It demonstrates Lee Precision's commitment to user-friendly design and efficiency.

The material choice of steel for all primary components ensures exceptional durability. Reloading equipment endures considerable force and repetitive action, and steel construction provides the necessary strength and resistance to wear, ensuring your investment in the Lee Precision Lube & Size Kit continues to perform reliably for many years.

How Bullet Sizing Works: A Step-by-Step Overview with Lee Precision

Using the Lee Precision Lube & Size Kit is a straightforward process, designed for efficiency and ease of use. While specific instructions for lubrication (such as Lee Liquid Alox) and your press operation are sold separately, the core sizing process follows a logical sequence:

1. Setup Your Single-Stage Press: Begin by securely mounting your Lee Precision Sizer Die into the appropriate threaded station on your single-stage reloading press. Ensure it is tightened down according to your press manufacturer's recommendations.
2. Install the Push Through Punch: Remove your standard shell holder from the ram of your press and replace it with the Lee Precision Push Through Punch. This punch will directly engage the base of your cast bullets.
3. Prepare Your Cast Bullets: Before sizing, ensure your cast bullets are clean and free of any debris. For optimal results and to reduce the force required, it is highly recommended to apply a suitable bullet lubricant, such as Lee Liquid Alox, before pushing the bullets through the sizing die. Lee Liquid Alox is specifically formulated to work seamlessly with this system, providing excellent lubrication and preventing lead buildup in the die.
4. The Push-Through Process: With the die and punch set up, place a cast bullet (nose-first) into the opening of the sizer die. As you operate the press handle, the ram will push the Push Through Punch, which in turn drives the bullet through the precision-machined sizing die. You will feel a consistent, smooth resistance as the bullet's diameter is uniformly reduced.
5. Gas Check Application (If Applicable): If your cast bullets require gas checks, the Lee Precision sizing die is designed to seat and crimp these checks onto the bullet base as it passes through the die. Ensure the gas check is properly oriented at the base of the bullet before pushing it through. The die's design will facilitate the secure attachment of the gas check.
6. Collecting Sized Bullets: Once the bullet passes completely through the die, it will drop into the integrated Sizer Box (bullet catcher) below. This keeps your sized bullets contained and organized, ready for the next stage of your reloading process.
7. Repeat and Reload: Continue this process for all your cast bullets. You'll quickly develop a rhythm, making bullet sizing a rapid and efficient part of your reloading routine.

This push-through design significantly simplifies the sizing process compared to other methods, eliminating the need for special nose punches or complex adjustments. It's a testament to Lee Precision's commitment to user-friendly and effective reloading solutions.

Why .001" Larger Than Groove Diameter? Achieving Optimal Fit and Performance

One of the most frequently asked questions by reloaders, especially those new to cast bullets, revolves around selecting the correct sizing die diameter. The general guideline, and one strongly recommended by Lee Precision and experienced reloaders, is to select a sizing kit that results in a bullet diameter approximately .001" larger than the groove diameter of your firearm's barrel. This might seem counterintuitive at first, but it is a critical factor for achieving superior accuracy and minimizing lead fouling.

Let's break down why this .001" oversized approach is so effective:

• Ensuring a Perfect Seal (Obturation): When a bullet is fired, the immense pressure of the burning propellant gases causes the base of the bullet to expand and "obturate" – meaning it swells to perfectly fill the bore. If a cast bullet is undersized, it won't obturate sufficiently to seal the bore. This allows hot gases to "gas cut" past the bullet, eroding its surface and leading to significant lead buildup in the rifling. An oversized bullet, even by a tiny fraction of an inch, ensures that it expands fully to seal the bore, preventing gas cutting and maximizing propellant efficiency.
• Consistent Rifling Engagement: An oversized bullet ensures consistent and full engagement with the barrel's rifling. This positive engagement imparts the necessary spin for stability in flight, leading to much greater accuracy. An undersized bullet may "skid" or "strip" in the rifling, resulting in wobbling and poor shot groups.
• Minimizing Lead Fouling: This is perhaps one of the most significant benefits. Gas cutting is the primary cause of lead fouling in barrels when shooting cast bullets. By ensuring a perfect seal and full engagement, the .001" oversized rule dramatically reduces, if not entirely eliminates, lead deposits in your barrel, leading to easier cleaning and prolonged accuracy.
• Accommodating Barrel Variations: Even within the same caliber, slight variations in barrel groove diameter exist from one firearm to another. By sizing your bullets slightly oversized, you build in a small tolerance that helps ensure a proper fit across a range of firearms chambered for that caliber.

To implement this, you'll need to accurately measure the groove diameter of your specific firearm's barrel. This can be done using a slugging process or by consulting reliable technical data for your firearm model. Once you have this measurement, simply add .001" to determine the ideal sizing die diameter for your cast bullets. For instance, if your barrel's groove diameter is .357", you would ideally choose a .358" sizing die.

Beyond the Basics: Advanced Tips for Maximizing Your Bullet Sizing Results

While the Lee Precision Lube & Size Kit simplifies the sizing process, adhering to a few best practices can further enhance your results, leading to even more precise and reliable ammunition.

• The Right Lubricant is Key: As mentioned, Lee Liquid Alox (sold separately) is highly recommended for use with this kit. Its thin, liquid consistency allows for easy application and effective lubrication, reducing the force needed to push bullets through the die and preventing lead from galling inside the sizer. Experiment with the amount of lubricant; typically, a light coating is all that's required. Too much can lead to sticky bullets or excess residue on your hands and equipment.
• Maintaining Your Sizing Die: Keep your sizer die clean. Over time, minuscule lead particles or lubricant residue can build up inside the die, potentially affecting future sizing consistency. Periodically clean the die with a bore brush and a suitable solvent to ensure its internal surface remains smooth and free of contaminants. A well-maintained die translates directly to consistent bullet dimensions.
• Consistency in Casting: While the sizing die corrects inconsistencies, striving for consistency during the bullet casting process itself will make sizing even easier. Consistent alloy temperature, pour speed, and mold temperature contribute to more uniformly cast bullets from the outset, reducing the amount of work the sizing die has to do and potentially extending its life.
• Understanding Your Alloy: Different lead alloys have varying hardness levels. Softer alloys may size more easily but might require gas checks at lower velocities to prevent leading. Harder alloys might require more force to size but can often be driven at higher velocities without gas checks. Understanding your alloy's properties will help you optimize your sizing and loading parameters.
• Synergy with Your Reloading Press: While the Lee Precision Lube & Size Kit is designed for single-stage presses, the quality and stability of your press matter. A robust press with minimal flex will provide a more consistent and repeatable sizing stroke, contributing to superior results. Ensure your press is securely mounted to a sturdy workbench.
• Post-Sizing Inspection: After sizing, it's a good practice to visually inspect a sample of your bullets. Check for any inconsistencies, nicks, or imperfections. While the sizing process corrects diameter, it cannot fix deep flaws from casting. For critical loads, you might consider using a micrometer to spot-check the diameter of a few sized bullets to confirm they are within your desired tolerance.

The Lee Precision Advantage: Engineering for the Everyday Reloader

Lee Precision has long been a respected name in the reloading community, renowned for its innovative designs that combine efficiency, affordability, and robust performance. The Lee Precision Lube & Size Kit (Model 90037) embodies this philosophy, offering distinct advantages that make it a preferred choice for reloaders across all experience levels.

• Simplicity and Efficiency: The core genius of the Lee Precision sizing system lies in its straightforward push-through design. This eliminates the complexity and cost associated with multiple nose punches and more intricate sizing setups. It's a "set it and forget it" system that allows reloaders to quickly process large batches of bullets with minimal fuss. This direct approach not only saves time but also reduces the potential for error, leading to more consistent results for every bullet.
• Durability of Steel Construction: Investing in reloading equipment means seeking tools that can withstand the test of time and repetitive use. The primary components of the Lee Precision Lube & Size Kit – the sizer die and push-through punch – are crafted from high-quality steel. This material choice ensures exceptional durability, resistance to wear, and consistent performance over countless sizing operations. It's a testament to Lee Precision's commitment to building tools that last, providing excellent long-term value to the reloader.
• Cost-Effectiveness and Value: Lee Precision is known for providing high-quality reloading solutions that are accessible without compromising performance. The Model 90037 kit is no exception. It offers an effective and reliable bullet sizing solution at a price point that makes it an attractive option for both new and experienced reloaders looking to optimize their cast bullet operations without a significant financial outlay. This kit represents a smart investment for anyone serious about the economy and precision of their handloads.
• Brand Trust and Support: With decades of experience in the reloading industry, Lee Precision has built a reputation for innovative, user-friendly products and dedicated customer support. Choosing a Lee Precision product means investing in a brand trusted by a global community of reloaders. This reliability and widespread use translate into readily available resources, advice, and a proven track record of helping reloaders achieve their goals.
• Availability at DEGuns: Like many essential reloading components and tools from Lee Precision, the Lee Precision Lube & Size Kit (Model 90037) is readily available at DEGuns. DEGuns offers a comprehensive selection of reloading supplies, ensuring you can easily acquire this kit and all necessary accompanying items, such as Lee Liquid Alox and a compatible single-stage press, to complete your bullet sizing setup. Their extensive inventory and commitment to serving the reloading community make them an ideal source for all your handloading needs.

Frequently Asked Questions About Bullet Sizing and the Lee Precision Kit

Here are answers to common questions about bullet sizing and the Lee Precision Lube & Size Kit, addressing concerns and providing clarity for reloaders.

Can I use the Lee Precision Lube & Size Kit with jacketed bullets?

No, this kit is specifically designed for use with cast bullets. Jacketed bullets typically do not require sizing as they are manufactured to very precise tolerances. Attempting to size jacketed bullets with this kit could damage the bullet or the die, as they are significantly harder than lead or lead alloy cast bullets.

What type of reloading press do I need to use this kit?

The Lee Precision Lube & Size Kit is intended for use exclusively on single-stage presses. Its design, which involves pushing the bullet completely through the die, is optimized for the leverage and direct action provided by a single-stage press. While some progressive presses might theoretically be adapted, the most efficient and recommended setup is a single-stage press.

What kind of lubricant should I use with this kit?

For optimal performance and to prevent lead buildup in the die, Lee Liquid Alox is highly recommended and sold separately. It is specially formulated to work with Lee's push-through sizing system. Other bullet lubricants may work, but Lee Liquid Alox offers superior compatibility and ease of application for this specific process.

How do I determine the correct size of the sizing die to purchase?

You should select a sizing kit that results in a bullet diameter approximately .001" larger than the groove diameter of your firearm's barrel. For example, if your barrel's groove diameter measures .357", you would typically choose a .358" sizing die. Measuring your barrel's groove diameter is the most accurate way to ensure an optimal fit.

Is this kit difficult to use for beginners?

Not at all. The Lee Precision Lube & Size Kit is celebrated for its simplicity and ease of use. Its push-through design eliminates complex adjustments or the need for multiple specialized parts. With clear instructions (included with the kit), even novice reloaders can quickly master the process of sizing their cast bullets effectively.

Can this kit also apply gas checks?

Yes, one of the key functions of the Lee Precision Lube & Size Kit is its ability to seat and crimp gas checks onto the base of cast bullets as they are pushed through the die. This streamlines the preparation process for bullets that require gas checks for higher velocity applications or to further reduce leading.

What is the UPC for this specific kit?

The Universal Product Code (UPC) for the Lee Precision Lube & Size Kit is 734307900373. This code can be used to identify and locate the specific product at retailers like DEGuns.

Elevate Your Reloading Journey with Lee Precision

The pursuit of perfection in handloading is an ongoing journey, and every precise step contributes to the ultimate goal of superior accuracy and performance. The Lee Precision Lube & Size Kit (Model 90037) represents an indispensable tool in this pursuit, transforming the often-overlooked task of bullet sizing into a seamless, efficient, and highly effective part of your reloading workflow. By ensuring consistent bullet diameters, optimizing bore fit, and facilitating gas check application, this kit directly contributes to tighter groups on target, reduced lead fouling, and an overall more rewarding shooting experience.

For those committed to maximizing the potential of their cast bullets and achieving unparalleled precision in their ammunition, investing in the Lee Precision Lube & Size Kit is a decision that pays dividends in accuracy, reduced maintenance, and the satisfaction of crafting truly custom ammunition. It’s an essential component for any reloader’s bench, embodying Lee Precision's commitment to quality, innovation, and value.

Discover the difference that precise bullet sizing can make in your reloading efforts. The Lee Precision Lube & Size Kit, along with all the necessary reloading supplies like Lee Liquid Alox and a wide range of single-stage presses, is readily available at DEGuns. Equip your reloading bench with the tools trusted by reloaders worldwide and take the next step in perfecting your handloads.

Product Specifications and Compatibility

Brand	Lee Precision
SKU	90037
UPC	734307900373
Series	Kit
Model	Classic Bullet Sizing
Function	Size Bullet, Lubricate Bullet, Seat Gas Checks, Crimp Gas Checks
Material	Steel (Die, Punch)
Compatible Press Type	Single Stage Presses (Standard 7/8 x 14 Threads)
Includes	Sizer Die, Push Through Punch, Sizer Box (Bullet Catcher)
Media Type	Cast Bullets (Lead / Lead Alloy)
Recommended Lubricant	Lee Liquid Alox (Sold Separately)
Weight	Approximately 0.99 lbs (1 Kit)
Key Feature	Push-through design, No special nose punches needed
Manufactured By	Lee Precision, Inc.