What is "over bore"?

Large powder capacity trying to be forced out a smaller bore??


Perry

Yes

Ideally, a rifle bore volume is exactly enough so that the very last grain of powder is consumed the instant the bullet exits the muzzle. Cartridges that are considered “overbore” have capacities so large for the bore volume that this isn’t possible. Characteristics of “overbore” include excessive blast and/or noise, and diminished velocity gains relative to increased powder charge, eg. “less efficient” cartridges. For example, Dan Lilja wrote an interesting article a number of years ago on optimal barrel length needed for the .338 Lapua cartridge. I seem to remember he determined a minimum length of 34” was necessary to take advantage of such a large case capacity, and even longer would be better.