I was loading some .338 RUM loads the other day and was using a caliper to measure each load for OAL. I was loading 250gr Barnes X bullets. Most loaded cases measured a certain length but a few loads, probably 10% were longer than all the others. How could this happen? Even if the cases were different length, the press should have taken the difference out by seating the bullets deeper. I believe all the bullets came from the same boxes so the ogive should be identical on each one. What gives?

this is because the die that swags the jackets does not always break the copper off the same. There is no meplat trimming process in factory ammo,..so the main difference comes at the tip. Use a comparator to ensure that the ogive to casehead is the same on each round.

Thank you I'll try that next.