Browning A Bolt Long Action Detachable Bottom metal. Finish the job the factory forgot to do. Add a Box mag to your Rifle. These rifles are very nice and this upgrade takes it to the next level. Works with 300 Win Mag or 338 Lapua AI mags. This Bottom metal assembly allows the use of AICS magazines in your Browning A Bolt. Install is required, and we can provide inletting and install services as well. Installs are free at CDiPrecision, so click Install option and send your rifle in for install. Easy and fast. 3 week turnaround or faster. US Addresses only. Mags Must be purchased Separately.