Having started this thread to get some conversation going and not knowing then where that discussion would lead (and in fact learning from some of it), I personally don’t think we are straying, merely meandering through some of the many interesting facets brought out by this thread.
Experimental projectiles from places like Milledgeville or the West Point range, unfinished, apparently not distributed types found only at arsenal dump sites, and ones on that have only been found on ships like the Brittens off the Georgiana prove these things to have been part of the larger context of the American Civil War, but as RedBob wrote, it is a collectors own feelings that determine whether one thinks of these in the same way as that individual regards battlefield recovered specimens. I know for a lot of folks, shells not having been actually used in combat fired at the enemy is an asterisk (& some collectors of their own prerogative may even go so far as to not want to collect them as a result – aka Carl’s politics reference and lets please not go there as Scott is a skilled debater who will happily take on all comers in that area). My personal choice is that I have in my collection a number of projectiles, and some fuses, from all the places listed above and I still think they are cool even if in my mind of minds the ones with verifiable battlefield usage have a little more interesting history to me.
I never knew these detached nose Whitworths made it even to our shores as early as 1862. It would seem logical that in the ensuing 3 years some like them were used in battle, but I am not aware of them. I don’t think the Gettysburg projectiles stacks are good proof of that. Speaking only personally but to me it would be be very, and even more interesting, to confirm some actually got fired in battle here. Still, as I mentioned for me their presence in a blockade runner alone elevates them historically for what I am interested in from the vast amount of Whitworth projectiles that are out across the globe or were imported after by places like Bannermans that never were even considered for use here during the ACW or after even. For me, as a personal choice, that is where I generally draw the line. BUT as you can see, I made an exception with the Baby Whitworth because it too is neat in its own right and I had seen war dated Baby Whitworth cannon out in my South American travels. So, in sum, I guess there are no firm rules, only individual collector preference.