Precision Reloading for .357 Magnum and .38 Special: Mastering the Crimp with Lee Dies

For anyone serious about handloading ammunition for their .357 Magnum or .38 Special firearms, achieving a perfect crimp is not just a preference—it’s a critical component of safety, consistency, and accuracy. The Lee 90781 Taper Crimp Pistol Die for .357/.38 Special is an indispensable tool designed to elevate your reloading process, ensuring every round you produce meets the highest standards of quality and performance. Whether you're a seasoned reloader seeking to fine-tune your loads or a newcomer looking to prevent common reloading pitfalls, understanding the role of a precision crimp die like this one is paramount.

The Fundamental Importance of Ammunition Crimp

What exactly is crimping, and why is it so vital? In the context of reloading, crimping refers to the process of applying pressure to the mouth of the cartridge case, either to secure the bullet in place or to improve powder ignition. This seemingly minor step has profound implications for the finished cartridge:

• Bullet Retention: The primary function of crimping is to hold the bullet firmly in the case, preventing it from moving either deeper into the case (bullet setback) or pulling out of the case (bullet jump) before firing.
• Consistent Pressure and Powder Ignition: A proper crimp provides resistance against the bullet's movement as the powder ignites. This resistance allows internal pressure to build consistently, which is crucial for a complete and uniform powder burn. Consistent ignition translates directly into more consistent muzzle velocity and, consequently, tighter groups downrange.
• Reliable Feeding and Function: For semi-automatic firearms, a well-crimped round ensures smooth feeding from the magazine into the chamber. For revolvers, it prevents bullets from "jumping" forward under recoil, which can cause the cylinder to bind and prevent subsequent shots.
• Enhanced Accuracy: By ensuring consistent neck tension and powder ignition, a precise crimp minimizes shot-to-shot velocity variations, leading to improved accuracy and predictability in your reloads.
• Prevention of Bullet Damage: An incorrectly applied crimp can deform the bullet, leading to accuracy issues or even fliers. A precision die helps avoid this.

Without a consistent and appropriate crimp, you risk unreliable ammunition, reduced accuracy, and in some cases, dangerous pressure excursions or malfunctions. This makes the crimping stage one of the most important in the entire reloading process.

Exploring Crimp Types: Why Taper Crimp Excels for .357/.38 Special

There are generally three main types of crimps used in reloading: roll crimp, taper crimp, and factory crimp. Each has its specific applications and advantages.

Roll Crimp

A roll crimp is created by rolling the mouth of the case inward, into a cannelure (a crimp groove) on the bullet or simply over the bullet's edge.

• When it's traditionally used: Most commonly seen on revolver cartridges like the .357 Magnum and .38 Special, where recoil is significant, and maximum bullet retention is desired. It's also used for rifle cartridges.
• Disadvantages: Requires bullets with a cannelure to be most effective. Can potentially over-crimp and deform the case mouth or bullet if not set correctly. Not ideal for semi-automatic pistols where cartridges headspace on the case mouth.

Taper Crimp

A taper crimp, as facilitated by the Lee 90781 die, applies a gentle, inward squeeze to the case mouth, tapering it slightly to grip the bullet firmly.

• How it works: Instead of rolling the case mouth over, the taper crimp die applies pressure uniformly around the circumference of the case mouth, gradually reducing its diameter to secure the bullet.
• Key Advantages for Pistol Ammunition:
  • Versatility: Does not require a crimp groove (cannelure) on the bullet. This makes it ideal for lead, plated, and many jacketed bullets that lack cannelures, preventing bullet deformation.
  • Headspacing Preservation: Crucial for semi-automatic pistol cartridges that headspace on the case mouth. A taper crimp preserves the integrity of the case mouth, allowing for proper chambering and reliable ignition. While .357 Magnum and .38 Special are primarily revolver cartridges, some semi-automatic firearms (e.g., Desert Eagle in .357 Magnum, or custom builds) do chamber these rounds, making a taper crimp essential for reliable feeding in such platforms.
  • Reduced Case Wear: The gentler action of a taper crimp puts less stress on the brass, potentially extending the life of your cartridge cases.
  • Precision and Consistency: Offers fine control over the amount of crimp applied, leading to highly consistent results.
• Why choose a Taper Crimp for .357/.38 Special? While traditionally roll crimps are associated with these calibers due to their revolver application, the Lee 90781 Taper Crimp Die offers distinct advantages:
  • Using Lead or Plated Bullets: If you're using lead or plated bullets that don't have a cannelure, a taper crimp prevents the bullet from being swaged down in diameter, preserving accuracy and minimizing leading in the barrel.
  • Enhanced Consistency: For those chasing the tightest groups, the consistent neck tension provided by a taper crimp can often surpass the consistency achieved with a roll crimp, even in revolvers.
  • Preventing Bullet Jump Without Over-Crimping: A well-applied taper crimp can still provide ample bullet retention for most revolver loads, effectively preventing bullet jump under recoil without the risk of over-crimping that a roll crimp might present.
  • Modern Reloading Philosophy: Many modern reloaders prefer the precision and versatility of a taper crimp across a broader range of handgun calibers, including those traditionally roll-crimped.

Factory Crimp

The Lee Factory Crimp Die is a unique design that applies a collet crimp, squeezing the case mouth tightly around the bullet. It's often used as a final sizing step. While very effective, the Lee 90781 specifically focuses on the precision of a taper crimp.

The Lee 90781 Taper Crimp Pistol Die: Engineered for Excellence

Lee Precision is a name synonymous with innovation and value in the reloading community. The Lee 90781 Taper Crimp Pistol Die is a prime example of their commitment to providing reloaders with tools that solve real-world problems.

Designed to Overcome Common Crimp Problems

The original design philosophy behind the Lee taper crimp dies, including the 90781, was to overcome crimp problems often caused by "poor die design" or outdated methods. This refers to issues such as:

• Inconsistent crimps: Leading to erratic velocities and poor accuracy.
• Bullet distortion: Especially problematic with soft lead or plated bullets, where a heavy roll crimp can deform the bullet and ruin accuracy.
• Case mouth damage: Over-crimping can crack or prematurely wear out brass cases.
• Feeding malfunctions: Particularly in semi-automatic firearms where excessive crimp or incorrect headspace can cause stoppages.

The hardened steel construction of the Lee 90781 ensures durability and consistent performance over countless reloading cycles. This die is built to last and provide reliable results every time.

Addressing the "1986 or Newer Lee Dies" Context

The manufacturer notes that these dedicated taper crimp dies offer "little or no advantage when used with 1986 or newer Lee dies as the crimp angle is already modified taper crimp." What does this mean for you?

It indicates that Lee Precision continuously improves its standard reloading dies. Many Lee seating dies produced since 1986 incorporate a built-in "modified taper crimp" feature. However, a dedicated taper crimp die like the 90781 still offers distinct benefits:

1. Separate Operation: Using a dedicated crimp die allows you to separate the bullet seating and crimping operations. This is often recommended for maximum precision, as it prevents any potential distortion of the bullet during crimping, which can sometimes occur if seating and crimping are done in a single step with a combination die. It also allows you to fine-tune each parameter independently.
2. Ultimate Control: While standard Lee dies may offer a basic taper crimp, the dedicated 90781 die provides more precise and adjustable control over the crimp, letting you achieve the exact amount of tension desired for your specific bullet and firearm.
3. Troubleshooting: If you are experiencing issues with bullet setback or consistency, a dedicated taper crimp die can often resolve these problems, even if your other dies are newer Lee models. It ensures that the crimp is applied uniformly and precisely.

Versatility for Jacketed and Lead Bullets

A common misconception is that taper crimps are only for semi-auto pistol cartridges. For .357 Magnum and .38 Special, while traditionally roll-crimped, the Lee 90781 Taper Crimp Die offers significant advantages, especially when using modern bullet designs or seeking specific performance characteristics.

• No Crimp Groove Required: A key benefit of a taper crimp is that it does not require a crimp groove (cannelure) on the bullet. This makes the Lee 90781 die incredibly versatile for various bullet types, including:
  • Lead Bullets: Prevents swaging down the bullet's diameter, preserving its accuracy and reducing leading in your barrel.
  • Plated Bullets: Similar to lead, plated bullets can be easily damaged by an aggressive roll crimp. A taper crimp offers a secure hold without stripping the plating.
  • Jacketed Bullets: Many modern jacketed bullets for handgun calibers do not feature a crimp groove. The Lee 90781 allows you to securely crimp these bullets for reliable performance.
• For Jacketed Bullets with Crimp Grooves: If you are using jacketed bullets that do feature a crimp groove (common for some heavier revolver bullets designed for a roll crimp), the Lee 90781 Taper Crimp Die will still provide an effective and secure crimp. While the taper crimp doesn't bite into the groove like a roll crimp, it still applies consistent pressure to the case mouth, working in conjunction with proper neck tension to hold the bullet firmly. For maximum bullet retention in high-recoil .357 Magnum loads, some reloaders might still prefer a roll crimp if the bullet has a cannelure, but for many applications, the precision of a taper crimp is more than sufficient and often preferred for consistency.

Optimizing Your Reloading Process with the Lee 90781 Die

Integrating the Lee 90781 Taper Crimp Pistol Die into your reloading setup is straightforward, but a few considerations can help you achieve optimal results:

1. Setting Up the Die:
   • Thread the die into your press until it lightly touches the shell holder (with a case in place).
   • Back the die out one or two full turns.
   • Insert a charged, bullet-seated case into the shell holder.
   • Slowly screw the die down, testing the crimp on a case, until you achieve the desired amount of crimp. The goal is to just remove the bell from the case mouth and apply slight pressure. You should not see any deformation of the case shoulder or bullet.
   • Consult your reloading manual for specific crimp recommendations for your bullet and powder combination.
2. Achieving Consistent Results:
   • Consistent Case Length: Trim your cases to a consistent length. Variations in case length will lead to inconsistent crimps.
   • Proper Neck Tension: Ensure your sizing die provides adequate neck tension. The crimp should primarily remove the flare and provide additional bullet retention, not be the sole means of holding the bullet.
   • Clean and Lubricated Brass: Use clean brass and proper case lubrication (if required for your sizing die) to ensure smooth operations.
3. Troubleshooting Common Crimp-Related Issues:
   • Bullet Setback: If bullets are pushing deeper into the case when chambered or under recoil, increase the taper crimp slightly. The Lee 90781 is excellent for preventing this.
   • Inconsistent Accuracy: Erratic velocities often stem from inconsistent crimp. A precise taper crimp helps standardize powder ignition, improving group sizes.
   • Feeding Problems (for Semi-Autos): If rounds don't chamber smoothly, ensure the crimp isn't too heavy, which can create a slight bulge, or too light, which can leave a flared case mouth. The Lee taper crimp die helps create a clean, uniform profile.
   • Cracked Case Mouths: If your cases are cracking around the mouth after crimping, you're likely applying too much crimp or your brass is fatigued. Back off the crimp slightly.
   • Leading or Plating Stripping: For lead or plated bullets, excessive crimp can deform the bullet. The gentle, uniform pressure of a taper crimp minimizes this risk.

Addressing Common Questions for .357 Magnum and .38 Special Reloaders

The Lee 90781 Taper Crimp Pistol Die is the answer to many questions reloaders have, particularly for these popular revolver calibers:

• "How can I improve the accuracy of my .357 Magnum reloads?" A consistent crimp is a cornerstone of accuracy. By ensuring uniform bullet pull and consistent powder ignition, the Lee Taper Crimp Die helps minimize velocity spreads, directly leading to tighter groups.
• "What's the best way to prevent bullet setback in my .38 Special ammunition?" Bullet setback can be dangerous. The Lee 90781 applies a firm, even crimp around the bullet, significantly reducing the likelihood of setback, even with repeated chambering or under recoil in revolvers.
• "Are taper crimps suitable for revolver cartridges like .357 Magnum?" Absolutely. While roll crimps are traditional, a well-executed taper crimp with the Lee 90781 provides excellent bullet retention for the vast majority of .357/.38 Special loads, especially when using bullets without a cannelure or when consistency is paramount.
• "Which crimp die should I use for lead bullets in my .38 Special loads?" The Lee 90781 Taper Crimp Die is an ideal choice for lead and plated bullets. Its gentle, uniform pressure secures the bullet without deforming the soft lead or stripping the plating, preserving accuracy and reducing barrel leading.
• "My reloads are inconsistent – could it be the crimp?" Very likely. Inconsistent crimp is a leading cause of velocity variations and poor accuracy. The precision engineering of the Lee 90781 ensures a uniform crimp every time, greatly improving the consistency of your ammunition.

The Lee Precision Advantage: Quality and Innovation You Can Trust

Lee Precision has earned its reputation by providing innovative, high-quality, and user-friendly reloading equipment accessible to reloaders of all experience levels. Their dedication to thoughtful design, evident in products like the 90781 Taper Crimp Die, ensures that you are investing in a tool that will enhance your reloading experience for years to come.

When you choose Lee Precision products, you're opting for:

• Reliable Performance: Engineered for consistent, repeatable results.
• Durability: Constructed from hardened steel and robust materials designed for longevity.
• Innovation: Lee consistently introduces new ideas and improvements to the reloading process.
• Value: Providing exceptional quality and performance without an exorbitant price tag, making advanced reloading techniques accessible.

The Lee 90781 Taper Crimp Pistol Die is more than just a piece of equipment; it's an investment in the quality, safety, and performance of your handloaded .357 Magnum and .38 Special ammunition. By providing a precise and consistent crimp, it ensures your rounds feed reliably, ignite uniformly, and achieve superior accuracy downrange. This tool is a testament to Lee Precision's commitment to empowering reloaders with the best possible equipment for their craft. All genuine Lee Precision products, including this essential Taper Crimp Die, are available for purchase from trusted retailers like DEGuns.

Product Specifications

Feature	Detail
Brand	Lee Precision
Model	Taper Crimp Die
Caliber	.357 Magnum / .38 Special
Purpose	Ammunition Crimping
Die Count	1 Die (Individual)
Material	Hardened Steel
SKU (Internal)	40747
UPC	734307907815
MPN	90781