One of the problems when trying to learn about rare and unusual firearms (rare and unusual anything, actually) is the lack of primary source material. In other word, information about the gun written by someone with direct experience, not information compiled by a second party. Part of the reason we really like original manuals is that they convey information directly from a gun’s manufacturer, and can almost always be relied upon for accuracy. The same goes for military trials reports, although one must keep in mind potential biases on the part of testing officials.
However, this sort of material is often not available for the really interesting guns, and one if forces to rely on secondhand descriptions whose provenance can’t be determined. It is not uncommon for a writer many decades ago to have mixed up some fact, and then had his mistake repeated by many other authors using him as a source, until you get to the point where the mistake is taken as gospel truth (and recorded as such on Wikipedia).
A perfect example of this is the Italian early selfloading Cei Rigotti rifle. Everyone knows that, being made in Italy, these rifles are chambered for the standard 6.5mm Carcano cartridge. Well, some folks who have access to a Cei Rigotti in the US recently posted this video discussing it, and pointed out that theirs is actually in 7.65×53 Mauser caliber. We have looked at two different examples of the rifle in Europe, and never bothered to look closely at the bores, because hey, everyone knows they’re in 6.5mm. But after seeing that video, we spoke with the Pattern Room curator, who checked and confirmed that their Cei Rigotti is also actually in 7.65×53. The second one we know of is in storage at the moment, but we will be following up to get a confirmation of its actual caliber when it is unpacked.
In retrospect, a 7.65mm chambering would make perfect sense, as the Cei Rigotti was floated to several different countries in hopes of getting a military contract. Carcano ammunition wouldn’t have been widely available outside Italy, but the 7.65×53 was a standard Mauser caliber and would be more readily available and recognizable to potentially interested buyers. The question now is whether all the the Cei Rigottis are in 7.65, or if they were made in two or three different calibers for different markets. We may never be able to know that for sure, since there are only a handful of them still in existence.