300 RUM Nosler brass
27 inch 7 twist barrel
CCI 250
205 grain SBDII
3.019" BTO = 0.020" off the lands
Retumbo
89.0 = 3,223
89.5 = 3,212
90.0 = 3,230
90.5 = 3,241 flat primer
91.0 = 3,251 flat primer
91.5 = 3,261 flat primer
92.0 = 3,334 bolt lift, ejector
92.5 = nope
First shot was the high left then it migrated to the center and the last shot was the high right. I have loaded for several RUMs that run the Berger 230 at ~2,980 with 89.0 grains of Retumbo so that's where I started. I'll probably load 88.5 to 90.0 and shoot it at distance
Edit; I have had to drill two 2 seating stems out with a 1/8" drill because the long aluminum tip was bottoming out. Had a few measurements that had me scratching mu head before I realized what was going on.
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