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Not sure of any cartridges in that size. I know Ron Smith could make you a barrel though. Some Province, or State, or Country had a .29 caliber minimum, so the guy wanted a .290 at all costs. He also paid for all the tooling without question, surprisingly enough.
The 280 Jeffery is .288", and the 7.35 Italian Carcano is .298 if you are looking for calibers between .284 and .308, there are a few other oddballs as well.