Yep, common with custom barrels--some makes more so than others.
Also, it may have a shorter than standard throat. From the load you mentioned in the Speer manual, I deduced it's a 7x57. Throat dimensions can be all over the place in 7x57s, but for custom-barreled rifles, gunsmiths often use reamers with shorter throats, which give bullets less chance to tilt a little before entering the rifling.
