In my case, about 2 thou of neck tension for a .308 Win, packed inside the blue Dillon 50rd boxes. I'd trim to fit a layer or two of the thin foam that comes in boxes of Berger bullets in the top of the ammo boxes to cushion the tips (and to help keep the empties from coming out). It was absolutely solid for every day handling and bumping around, and *usually* fine for travel. Usually I had the blue Dillon boxes stuffed into a small Pelican style hard case, fitted with pick-n-pluck foam inserts. You can fit a fair bit of ammo in a case like that
Every once in a blue moon, I'd get some weirdness happening downrange on target. One such time, it just so happened that I had some 'saved' rounds left over, and while sitting around the hotel room bitching about what had gone wrong with my gun, borrowed some measuring tools. The CBTO was very much not what it was supposed to be. Knowing that the comparator I was using at the time wasn't necessarily the same as 'my' comparator at home, I wasn't betting the farm on that reading - but it was a hint. I very carefully packed up that partial box of ammo in my luggage, and checked it again when I got home with my own tools. Yup, definitely moved. After that, I started looking for ways to make sure I didn't get 'bit' by that particular gremlin again.
Some of these trips were 1000-1500 miles (each way) of interstate and highway, or flying with multiple lay-overs. Sometimes the ammo was shipped ahead via UPS, because 5 kilos / 11 lbs of ammo just wasn't enough to shoot an entire event. Some were international trips where the ammo had to be pre-loaded months in advance, shipped to a team sponsor (Berger, at the time), then shipped via container through their agents so it had time to go through customs and we picked it up from secure storage when we arrived.