Description
The Underwood 380 ACP 90gr Penetrator load, Underwood item 643, is a 20 round box of 380 ACP ammunition loaded with a 90 grain Xtreme Penetrator bullet rated at 1100 fps with 242 ft-lbs of muzzle energy.

Underwood 380 ACP 90gr Penetrator Overview
Underwood Ammo builds high-performance ammunition in Sparta, Illinois, and is known for loading cartridges to their full potential. Many Underwood loads run faster than typical factory ammunition while staying within safe pressure limits, and the company pairs that speed with premium bullets from makers such as Lehigh Defense and Hornady. Cases are nickel plated for smooth feeding and corrosion resistance.
Bullet Design
The Xtreme Penetrator bullet, designed by Lehigh Defense, is a solid copper projectile with a unique fluted nose. It is built for maximum penetration, and Underwood says it creates a larger permanent wound column with over twice the penetration of most expanding bullets. Its blunt nose helps it feed reliably, and its lead-free construction makes it a fit where lead-free ammunition is preferred.

Intended Use
This load is built for personal protection where deep penetration through heavy clothing and barriers matters, and it also works as a woods carry load for protection against animals. Its solid copper construction will not fragment or shed its jacket. Always confirm reliable feeding and point of impact in your own firearm before you rely on it.
Firearm Compatibility
This ammunition is made for firearms chambered in 380 ACP. Always check the caliber marking on your barrel or slide before loading. Underwood loads run at the upper end of safe pressure for the cartridge, so make sure your firearm is in good condition.

About Underwood Ammo
Underwood Ammo is a family-run American company that has built a reputation for powerful, accurate ammunition. Each load is developed and tested in-house, and the company publishes velocity and energy figures for every product so shooters know exactly what they are getting.
Recoil and Shootability
Underwood loads tend to produce more recoil and muzzle blast than standard practice ammunition. Practice with the load you carry so follow-up shots stay fast and accurate.
Why Shooters Choose Underwood
Shooters choose Underwood because the published numbers are real and the loads deliver them. Pairing premium bullets with carefully developed powder charges gives each load a clear purpose, whether that is defense, hunting or practice. Nickel or brass cases, quality primers and careful loading round out a product that many shooters trust when performance matters most.
Practice and Testing
Fire a few magazines or cylinders of this load before relying on it for defense or hunting. Confirm reliable feeding, extraction and point of impact, since fast or heavy loads can print to a different point than practice ammunition.
Choosing a Load
Choose your bullet for the job: solid copper fluid-transfer bullets for defense through barriers, expanding hollow points for controlled expansion, and hard cast or penetrator designs for large animals. Then pick a weight and speed you can shoot accurately.
Storage and Care
Store ammunition in a cool, dry place in its original boxes, away from solvents and lubricants that can contaminate primers. Inspect rounds before loading, and set aside any with dents, loose bullets or corrosion.
Specifications
- Brand: Underwood Ammo
- Item number: 643
- Caliber: 380 ACP
- Bullet weight: 90 grain
- Bullet type: Xtreme Penetrator (solid monolithic copper)
- Muzzle velocity: 1100 fps
- Muzzle energy: 242 ft-lbs
- Case: Nickel
- Lead-free: Yes
- Count: 20 rounds per box
- UPC: 816874020057
- Made in the USA
- Photo note: one gallery photo shows a related Underwood load, included to show the packaging style.
Before You Buy
Federal law requires buyers of handgun ammunition to be at least 21 years old when buying from a licensed dealer. Some states and cities restrict ammunition purchases, require background checks or limit shipping, so check your local rules before you order.
Who It Is For
The Underwood 380 ACP 90gr Penetrator is a great fit for shooters who want high-performance 380 ACP ammunition from an American maker known for powerful, accurate loads.
Buy the Underwood 380 ACP 90gr Penetrator at MAG5 Firearms
MAG5 Firearms is a family-owned FFL in Collegeville, Pennsylvania. Order the Underwood 380 ACP 90gr Penetrator online and we will ship it to you where state and local law allow, or browse our full selection of ammunition for more handgun loads. For factory details, visit Underwood Ammo.





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