J.Chismore was a relative of the Remington's. (The Remington's of firearm fame.)
Here's a Facebook quote.
[
Jimmy McCullough
I have a half stock with p and Remington stamped underneath. It was made and signed by j Chismore who was elaphet Remingtons nephew the son of Elizabeth Remington. Camp Chismore in New York is named for him, he was caputured at Petersburg ( crater) and died th a pow camp. He made about 25 guns before joining the army.]
I didn't look up Warren and Steele.
Half stock rifle suits the Civil war era for new builds.
Double pinned and trigger guard style hint of Hawkins farther West . (St. Lewis around 1820 to start thier shop there.)
The cheek piece a bit fancy. And hints of earlier rifles like certain full stock "golden age" ones..
But builders had thier inspirations from multiple sources. And multiple "schools" of build existed over time .
The builder didn't make thier own lock (Warren and Steele did that ).
I don't know if J.C. made the octagon to round barrel or just put his mark on it.