Has Overbore Capacity Become Outdated?

THIS is a term used to designate a cartridge case that is too large to fill properly with any available and suitable powder, without building up excessive pressure. Over time, however, it became recognised that a cartridge case which is overbore capacity in a given calibre with one make and type of powder, may not be so, if a different, slower-burning powder was used.

Other factors affecting bore capacity are rifling depth, bore tolerances, pitch of rifling and sectional density of the bullet used. Case shape also plays a part to some extent.

Charles Newton designed some extraordinary rifles and cartridges during the late 1920s. At that time with the powders then available, they were badly overbore capacity and never gained the kind of popularity