Three dollars and some change

I was re-reading some old MCU fic, and in the fic Steve says that Bucky was named for President Buchanan. Which Doylistically he was, but ... there's no reason he has to be from an in-universe perspective.

"James" was an incredibly common first name. The Social Security Administration publishes lists of how popular various names have been over the years; in the 1910s, when James and Steve were born, "James" was the third most popular name for boys. 275,000 baby boys were named "James" in that decade, which, given the size of the population, means that there were a lot of James' everywhere. Very common name.

Ah, but what of Buchanan, you say! Surely there could be no reason to give someone the middle name "Buchanan" if it's not naming him after someone famous! ... and no, actually. While people sometimes were named after famous people or political leaders (just like today), there's actually a more common reason to do it. It was a fairly common thing in the 19th Century for people to have a "last" name as a middle name, often their mother's maiden name, and people still do that today sometimes. Steve's middle name is "Grant", for example; "Grant" was a relatively common surname but (at the time) extremely uncommon as a first name. Steve was almost certainly given the middle name "Grant" to honor someone whose last name was Grant; it was probably his mother's maiden name. Buchanan is a relatively common Scottish name; it's not one of the top ten or anything, but the Buchanan clan is one of respectable size and power. In the same way, there is a very good chance that James was given the middle name "Buchanan" to honor someone whose last name was "Buchanan," quite probably his mother. And for a first name they gave him the third most common name for boys, and maybe didn't realize that there was a President by that name. Especially if they were immigrants, or weren't very well educated. (A lot of people in that generation had only a grade school education, or maybe a middle school education; only 10% of all 14-17 year olds attended high school in the US in 1900; there were still states where even elementary school wasn't required until 1918!) James Buchanan is not one of the Presidents that people talk about much outside history classes, and even then, a lot of history classes don't go into a lot of detail on him besides "last President before the Civil War." Yes, he was a bad President and one of the reasons the US Civil War became inevitable, but there were a lot of factors that were a lot more important.

I think "we liked the name James, and we wanted to honor his mother's family by giving him their last name as a middle name" is a far more likely scenario than consciously deciding to name their kid after President James Buchanan.

On a completely different note, if you want to write an AU where Bucky escaped Hydra early and made a new life for himself ... there's a late-20th-Century composer named James Barnes. He wrote concert band music. Here are some of his pieces: Symphonic Overture, Symphony No. 2, Third Symphony ("The Tragic"), Fantasy Variations on a Theme by Nicolo Paganini, Alvamar Overture.