Not that I need much help most of the time... But I'm getting the itch for something really off the wall. Were there any doubles made in 303 Brit? Just seems right to me.

Yes, plenty. Seems hard to find one with good bores at a reasonable price. Maybe others have had different experiences? Most are regulated for heavy bullets too it seems, which is fine by me.

JPK

They do turn up quite frequently in auctions, the last I saw was a Rigby sidelock with Bissel rising bite regulated for the Mk 6 cordite round with 215 grain bullet.

Unfortunately the bores were none too good but it sold for over £6,000

In the 1890s, .303 doubles were quite popular and quite a few were made. However, like the .450, the .303 was restricted in India early on, and the British gun trade was heavily dependent on the Indian market. Old gunmakers records, like Army & Navy's, show quite a few .303 doubles prior to 1900, but very few afterwards. As a result, .303 doubles tend to be quite old. Of course, many were Metford rifled, which didn't mix well with Cordite. That's why it's difficult to find them with nice bores.

Mediums like .400/.350, .350 No. 2, and .400/.360 Purdey are a good alternative. They're easier to find in good shape, and brass and bullets are easy.
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"Serious rifles have two barrels, everything else just burns gunpowder."

infection is easy to cure - just takes a double shot