I have a custom made rifle in 300 RUM with a blue printed Remington action and 30-inch Luther Walther barrel 1/10 twist. This extra length usually generates additional speed of 350fps over a 26". I finally got my hands on a good supply of Nosler 210gr. Accubond LR's and am wanting info from anyone out there that has developed loads showing superb accuracy with the 210 in their 300RUM. I have been shooting the 200gr. Accubond with excellent groups of .402 at 200 yds with 90.3 gr. of Retumbo in the 200's but have been having problems duplicating anything closer than 1.31 with the 210's using Retumbo. I have also used Magnum but results are close to what Retumbo is giving me. I would like to continue with these two powders as I have approximately 8 pounds of each. Any ideas out there? I was advised to try RL-25. I don't know anything about this powder?? Any help would be appreciated.