I think in the US most who would want a 30 caliber rimmed cartridge about the size of the 303 would choose a 30-40 Krag instead of the 30-303. The Krag has a slightly shorter body and a little longer neck than the 303.

The 25 Krag used to be a popular wildcat.

Compare measurements here.
http://stevespages.com/page8d.htm


Bruce