It’s not unusual for two barrels of the same manufacturer, using the same loads, to vary 100 fps or more. Smoothness of the rifling, inside diameter or number of rounds previously fired can have a bearing. Cooler temperatures can lower velocities and warmer temperatures can increase them. Even variances between lots of powder can change velocities. There’s a lot of variables at work here, so the fact that your velocities are different is hardly surprising.