Barrel break in is as much metallurgical as it is physical. I hate to be the bad guy here but 25rds isn't breaking in a barrel, load development on a new isn't going to be stable, and there are too many variables changing until the bore has passivated.
@Dusty Stevens it may take 25% of a barrels life to become passive and stable, until that point the barrel will continue to change until full passivstion is reached, this is directly in regards to your comment. Once the barrels bore is hardened to its full potential(for that given environment) only then will it stay stable until erosion disrupts that stability. Most 223/308 based cartridges take on average 200-300 to fully harden, magnums take about half that. Powder plays a giant role in this, a 6.5CM the only had H4831SC shot through it took 2100rds to fully stabilize the surface hardness of the bore. Once it did, no more changes in velocity or seating depth. Again, whatever a barrel company recommends is fine but science rules everything. I always liken the "recommended" break in process to a tire dealer telling you that you're new tires need 30min of burn outs to be ready to use.