QuickLOAD predicts a muzzle velocity of 3,069 fps from a 300 RUM shooting a 200-grain .308 Nosler Accubond (product #54618) in front of 99.9 grains of Reloder 33, with a cartridge length of 3.598" (the SAAMI maximum), at a peak chamber pressure of 64,917 psi. Per QuickLOAD this would be the maximum safe load: 100.0 grains puts you over the SAAMI maximum peak chamber pressure of 64,977 psi. I strongly recommend you work up a load starting several grains down from that maximum load. See this thread for a broader set of 300 RUM recommendations: https://www.longrangehunting.com/threads/reloader-33-in-300-rum-data.107586/. Consider using the ladder method: https://precisionrifleblog.com/2012/07/13/creighton-audette-ladder-testing/.I get over 3,000 fps with a Berger VLD H 210 grain using Reloder 33 in my 300 RUM (26" barrel). I used to use Reloder 25 and 26, with a little less velocity.