12GA to 9mm Luger Shotgun Adapter Chamber Reducer 12GA to 10MM - Shotgun Adapter Precision machined from stainless steel Proudly made in the USA This adapter gives your 12 Gauge single or double shot break open shotgun the ability to fire a 10MM bullet. This adapter is precision machined from high quality stainless steel to the OD specifications of a 2 3/4 12GA shell. It will easily fit into your break open shotgun barrel and accept any 10 mm ammunition. After firing simply remove the adapter and tip upside down to remove the spent 10mm shell. A smooth bore is gently bored through the adapter for the bullet (no rifling). The 10mm bullet side is precision CNC machined to the exact chamber dimensions to accept 10mm ammunition (SAAMI chamber specifications). Adapter orientation is not important and the adapter will work in any position. Made in the USA on American machines by American workers ......... support USA made products and companies! Will fit any break open shotgun with 2 3/4" or 3" chambers Perfect for 'Preppers' or your Bug Out Bags. Carry one gun and have the ability to shoot not only 12GA shells but also 10mm ammunition. Surprisingly accurate! Not recommended for pump action or semi-auto shotguns. Designed for use with break-open style shotguns. Any ammunition pictured is for representation purposes only and is not included with this purchase. We've test fired these adapters and at 50 feet with an old junky shotgun (with no sights) we were able to achieve groups of 3"-5" easily.