Perfect Case Preparation for Loading the New Bullet Corp .223 Bullets

When it comes to precision rifle ammunition, the bullet is only half the story. The other half is proper case preparation. If your brass isn’t sized, cleaned, and expanded correctly, even the most advanced projectiles won’t perform to their full potential. With the release of our new .223 Rem 72gr RN and .223 Rem 90gr RN bullets, it’s the perfect time to talk about one of the most overlooked steps in reloading: neck and case mouth expansion.

Why Neck Expansion Matters

Copper-coated and polymer-coated bullets are softer than traditional jacketed bullets. If you seat them into an unprepared or overly tight case mouth, the bullet coating can be shaved, scratched, or damaged. This not only affects accuracy, but it can also cause leading or inconsistent chamber pressures.

Expanding the case neck ensures:

• A smooth, consistent start for bullet seating.

• Less runout (better concentricity).

• No damage to the bullet coating.

• More consistent neck tension, leading to tighter groups on target.

Step 1: Resizing and Cleaning

Before expanding the neck, make sure your brass is resized and cleaned. Run the cases through your full-length sizing die, then clean off any case lube. Clean brass prevents scratches and ensures your dies last longer.

Step 2: Neck Expansion with a Mandrel

This is where precision begins. Tools like the LE Wilson Expanding Mandrel Sizing Die or the Axis Precision Worx Expander Mandrel Set are excellent for this job.

Here’s how it works:

1. Insert the mandrel into the case neck.

2. The mandrel gently expands the neck to a controlled diameter.

3. Every case now has identical neck tension for bullet seating.

Unlike traditional sizing dies that rely on neck tension alone, a mandrel ensures consistent, repeatable results. This step is critical if you want match-grade performance out of your .223 loads.

Step 3: Case Mouth Flaring

Even after using a mandrel, the very edge of the case mouth may still be too sharp or tight. For flat-base or coated bullets, it’s best to add a small flare at the case mouth. This prevents the bullet from catching or shaving during seating.

The Lee Universal Case Expanding Die is a simple and effective solution. It doesn’t size the neck – it only adds a gentle flare at the mouth. Use just enough expansion to allow the bullet to start smoothly.

Step 4: Bullet Seating

Once your cases are properly prepared, you can move on to seating the new Bullet Corp .223 bullets. With an expanded neck and flared mouth:

• The bullet enters straight and true.

• The coating remains intact.

• Seating pressure is consistent across every round.

This translates into better accuracy, reliability, and long-term barrel life.

Step 5: Crimping the Case

The final step when loading your .223 reloads is crimping. Once the bullet is seated, a light and consistent crimp helps maintain proper neck tension and prevents bullet setback during feeding or recoil.

There are two main approaches:

• Taper Crimp – Applies a gentle squeeze around the case mouth without digging into the bullet. Ideal for coated bullets like ours, as it avoids damaging the coating.

• Factory Crimp (Lee Factory Crimp Die or similar) – Uses a collet system to apply a uniform crimp around the case mouth. This is popular for semi-auto rifles, ensuring reliable feeding and consistent ignition.

⚠️ The key with coated bullets is moderation. Apply just enough crimp to remove the flare from the case mouth and hold the bullet firmly in place. Over-crimping can cut into the bullet coating, reducing accuracy and performance.

By adding a precise crimp, you lock in the work you’ve done through neck expansion, flaring, and careful seating – resulting in consistent, reliable ammunition ready for the range.

Final Thoughts

Case preparation is the foundation of accurate ammunition. By incorporating neck expansion and case mouth flaring into your reloading process, you protect your bullets from damage and create consistent, reliable ammunition.

The new Bullet Corp .223 bullets are designed for performance – but to get the most out of them, give your brass the same attention to detail. Properly prepped cases will let these bullets shine, whether you’re shooting for competition or precision practice.