Re: 300 RUM 210 bergers
order a wyatt extended box magazine.
Product SPECS: Stainless steel. Capacity: ADL - 3 rounds, BDL - 2 rounds. Extended - 3.91" (9.62cm) long. Long Window Box 3.91" long. Fits Remington 700 long action. Short Window Box 3.06" (7.6cm) long. Fits Remington 700 short action. WSM - Standard - 2.95" (7.5cm) long, fits 700 short action and Model 7. Extended - 3.06" (7.6cm) long, fits 700 short action. Capacity two rounds. M-70 3.82" (9.7cm) long, fits Winchester Model 70 long action. Capacity three rounds.
You will have to modify your bolt stop, it takes about hour with some good bits and a dremel. Thats what I did to mine. Works like a charm.
Chuck in Boise