The Sinclair bullet seating depth tool has been a staple for handloaders aiming to maximize rifle accuracy for decades. The latest model is crafted from 1/4 inches ground and polished stainless steel, featuring one end designed for use with .17 Cal and .20 Cal rifles and the other end suitable for .22 Cal and larger. This tool enables users to determine the length of a loaded round that contacts the rifling. It is compatible with most bolt-action, single-shot and AR-type rifles. Included with the tool is a Delrin action guide, which fits most bolt-action rifles (0.69 inches diameter, suitable for Remington, Savage, Winchester and many Ruger models). For the most precise measurements, the Sinclair bullet seating depth tool utilizes your fire-formed brass and bullets, ensuring exact measurements every time. Additionally, guides are available for use with AR-15, AR-10 and Tubb 2000 rifles. This guide differs slightly from standard bolt-action guides, as it inserts into the back of the upper receiver with the bolt removed. The tool is then used as usual. For optimal results, pair this tool with our bullet comparators and a quality set of calipers to achieve repeatable and precise Base-To-Ogive measurements. The Sinclair bullet seating depth tool, engineered from high-grade stainless steel, precisely determines optimal bullet seating depth for rifle calibers ranging from .17 to .22 and beyond The product is compatible with most bolt-action, single-shot and AR-type rifles It includes a Delrin action guide and provides additional guides for AR-15, AR-10 and Tubb 2000 models To ensure accurate measurements, the system employs fire-formed brass and bullets For optimal results, it is recommended to use bullet comparators and calipers to achieve precise base to ogive measurements