One of the essentials of accurate reloading is precise bullet seating depth. Regulating this is widely regarded as fundamental to improved accuracy. The Lock-N-Load O.A.L. gauge is the most accurate, easy to use, and reliable method of obtaining this critical measurement. (For use of this gauge, you will need to purchase a Modified Case to fit your firearm's chamber, and thread it onto the gauge.) With proper use, gauge dimensions obtained will be accurate to .001 inch. Results such as this cannot be attained with competitive products, which use a simulated bullet with an arbitrary shape. This precision is what can make the difference between just so-so accuracy, and real tack-driver performance.