The Krag–Jørgensen rifle had some serious limitations compared to the new Mauser rifles being used by European armies; its 5-round capsule magazine was loaded one round at a time, rather than using a stripper clip into a box magazine, and the Krag–Jørgensen's single locking lug on the bolt made the action much weaker than the strong, two lug Mauser bolt, limiting the power of the round.

Initially the .30-01 cartridge was developed in 1901; also referred to as the .30 ball Model of 1901 - the ".30-01" or "Thick-rim",[3] the .30-01 used a bullet covered by an alloy made from copper and nickel and was the immediate predecessor of the .30-03.

The .30-03 cartridge was also a rimless design, which allowed better feeding through the box magazine than the old .30-40 Krag case.

This conversion was principally carried out at the Army's Springfield Armory arsenal repair shops.

It caused severe erosion of the bore of the rifle, due to the high pressures and temperatures needed to push the heavy bullet to the desired velocity.

It was also unfashionable since most countries were switching to a 7 or 8 mm cartridge firing a lighter, around 150 grains (9.7 g), spitzer pointed bullet at a higher velocity.