The very first double rifle I ever bought, in 1970, was a Cogswell & Harrison .375 2 1/2." It was much the same as yours, but not restored, of course, as yours is. Odd, that my stock grain pattern looked much the same as yours too. Eventually, I sold it, but now have, in my rather large collection of double rifles, several other doubles in same caliber, including one hammer gun, a Hollis, in prime excellent almost unused original condition (regulated for the 300 grain bullet), and a wonderful Westley Richards (regulated for the 270 grain bullet) that will shoot horizontal groups of one to two inches for as long as you care to shoot. Frankly, my C & H wasn't nearly as accurate as any of my present doubles in this caliber. Originally, my C & H came with many cases, made by Norma and marked .303 British, but cases were made longer and formed into .375 2.5" (I still have and use most of those original cases, though I don't have the C & H anymore). We don't have any trouble getting cases or bullets here in America, and I use a lot of Hawk bullets; find them most suitable. I have killed a lot of deer and similar sized animals with this caliber. It really isn't that slow in velocity, at around 2000 fps (similar to most all the British express cartridges at around 2000 fps), but, of course, compared to the flanged or rimless .375 mag., it is slower.