I am curious if anyone has experienced this. My load for my 6.5-284 is : 140gr VLD , 59gr Retumbo, Fed 215, Lapua brass, seating .075 off the lands, rifle 1:8 twist Cooper. Velocity 2965fps ,es 15 fps. I have reproduced this with different lots of Retumbo and with new or fired Lapua cases. My buddy replicated the load except for a different lot of Retumbo and primer and used a Norma case. His weight of powder was checked and it is 59 gr on my scale. The Norma case capacity is .5 gr less than my Lapua. Testing in the same rifle, same chronograph, same day. The load is consistantly 60 FPS slower (2900) than my load with the same ES. Accuracy is the same. I haven't tried my load in the Norma case yet. Could the variation be: Different powder lot Different primer lot Different case Combination of above Any similar experiences?