HORNADY B300 300 REM ULTRA LOCK-N-LOAD MODIFIED CASE

The Hornady Lock-N-Load Modified Case 300 Remington Ultra Magnum (B300) is a brass tool case for reloaders who use Hornady Lock-N-Load O.A.L. and Precision Gauges to set exact bullet seating depth in 300 RUM rifles. This B300 modified case for 300 Rem Ultra Mag works with those gauges so you can match cartridge overall length to your rifle’s chamber instead of relying only on manual data.

Key Features

• Manufacturer part number: B300
• Cartridge: 300 Remington Ultra Magnum
• Case family: Hornady Lock-N-Load Modified Case B Series
• Intended use: for use with Hornady Lock-N-Load O.A.L. and Precision Gauges
• Material: brass modified case
• Case body: manufactured to 300 Remington Ultra Magnum chamber dimensions within SAAMI specs
• Neck: neck made approximately 0.002 inch oversize to accept the same bullets you intend to load
• Case head: threaded at the case head with a fine thread to attach directly to Lock-N-Load gauges and keep the case square in the chamber
• Quantity: one modified case per package

Special Features

• The B300 modified case uses a fine threaded case head so it screws securely into Hornady Precision and O.A.L. Gauges and stays aligned while you move the bullet up to the lands.
• The slightly oversize neck lets a 30-caliber bullet slip into the case mouth easily while maintaining light grip for smooth, repeatable movement during length checks.
• Hornady builds the B300 to chamber-realistic dimensions for 300 Remington Ultra Magnum, giving you a more accurate seating depth reference than simulated test bodies.
• Interchangeable B Series modified cases like the B300 let you run one Hornady gauge body across multiple magnum calibers by swapping cases.

Practical Benefits

• The Hornady Lock-N-Load Modified Case 300 Remington Ultra Magnum (B300) gives you a repeatable way to find the cartridge length that fits your rifle’s freebore so you tune seating depth for accuracy rather than guessing from book lengths.
• Because the B300 case works with compatible straight and curved Hornady gauges, it fits many 300 RUM long-range and hunting rifles that accept the tool and lets you standardize your seating depth process across more than one gun.
• The brass construction and oversize neck let you test with the same bullets you plan to load, so the distance to the lands you measure transfers cleanly to your seating die setup.
• If you load 300 Remington Ultra Magnum for long-range or big game rifles, the Hornady Lock-N-Load Modified Case 300 Remington Ultra Magnum (B300) is a practical choice that helps your handloads match your chamber and perform the way you built them.