Well, I'm going to comment even though I have neither of the things you set up as criteria for want answers to!
I did just get the 45Colt cartridge and have been having a BLAST (literal) working with it. Very nostalgic, and cool!
I cast and the bullet I use is a 240gr LSWC from an H&G #502 mould. It is of the Elmer Keith design just originally for the 45AR. Mine drops from the mould right at 245gr.
Also, I don't have a S&W 25-5 or any Smith in 45Colt (yet)! Got you wondering why I even came to post in this thread, don't I?

What I do have is a new Ruger Blackhawk 45 Convertible, 45ACP & 45Colt with a 5 1/2" barrel. This thing is a tank with a nice trigger and is pretty accurate.
The load I used for this lighter bullet was 8.5gr Unique. Here are the chronograph results from it:
Low: 928fps
High: 974fps
Avg: 951fps
ES: 46fps
SD: 16fps
My notes say: "Accurate, easy recoil, not too smokey."
The rounds I made up for future plinking use were 9gr under the same bullet but I haven't ran them over the chronograph them yet.
19gr of 2400 gave me an average of 1151fps from the same firearm but it wasn't all that consistent across the screens. That load needs worked on a bit!
Of late, many have shared loads that are much hotter than normal 45Colt loads. After speaking with John Linebaugh, I am thoroughly convinced that the newer 25-5/625 platform can take those rounds too. The only problem being, shooting loose. Keep that in mind.