When the tiniest variable means winning or losing, you need precision tools for precision loads. The Hornady Lock-N-Load Modified Case attaches to the Lock-N-Load O.A.L. Gauge and allows you to use the bullet you intend to load to determine the overall length to within 0.001 inches. This is critical since many overall length gauges use a generic bullet shape which may not match your load. For the most precise loads you need the most precise tools. You need Hornady.Specifications and Features: Item Number: B7MMP Fits: 7mm PRC Chamber Manufactured to SAAMI Specifications Threaded at the Case Head 0.002" Oversized Neck Accepts Intended Bullet Overall Length Accurate to 0.001"