HORNADY A300M 300 WIN MAG LOCK-N-LOAD MODIFIED CASE

The Hornady Lock-N-Load Modified Case 300 Win Mag (A300M) 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 Winchester Magnum rifles. This A300M modified case for 300 Win Mag lets you match cartridge overall length to your rifle’s chamber instead of relying only on manual data.

Key Features

• Manufacturer part number: A300M
• Cartridge: 300 Winchester Magnum
• Case family: Hornady Lock-N-Load Modified Case A 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 Win Mag chamber dimensions
• Neck: neck made approximately 0.002 inch oversize to accept the same bullets you intend to load
• Case head: fine threaded head 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 A300M modified case uses a fine threaded case head so it screws securely into Hornady gauges and stays aligned while you move the bullet up to the lands.
• The slightly opened neck lets a 30-caliber bullet slip into the case mouth easily while remaining concentric, which helps you feel bullet movement clearly during overall length checks.
• Chamber-realistic dimensions give you a more accurate seating depth reference than generic test bodies or improvised cases.
• Interchangeable A Series modified cases like the A300M let you run one Hornady gauge body across many calibers by swapping cases.

Practical Benefits

• The Hornady Lock-N-Load Modified Case 300 Win Mag (A300M) 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 A300M case works with compatible straight and curved Hornady gauges, it fits many 300 Win Mag hunting and long-range 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 Winchester Magnum for long-range or big game rifles, the Hornady Lock-N-Load Modified Case 300 Win Mag (A300M) is a practical choice that helps your handloads match your chamber and perform the way you built them.