I shot Berger Factory 300 NM 230 Hybrids, first 10-15 rounds were about the same speed. By the end of the 100 rounds, they stabilized around 2915fps. But I was also getting a little EJS. The first 40 rounds, had a total SD of 18.5 and an ES of 85. Once I had a few hundreds down the barrel, the next 50 of the factory Bergers had an Avg of 2915, SD 8.7 and an ES of 38.5.
I bought 200, shot 100, then handloaded them, then needed another 100 cases for this years NF ELR, so shot the other 100. The last 50 I reseated to a more consistent seating depth, and recharged the powder (1.22gr ES of powder weight). Those 50 rounds were 2899 AVG, SD 4.6, ES of 18.6.