The more I study the pictures of this rifle, the more similarities I see to rifles made by Samuel Smith. I own four of them, and should have submitted pictures of them to the Museum and Library before now.
Samuel Smith was born in Pennsylvania in about 1801. He is listed in the 1850 census as a gunsmith in Astoria Township, Fulton County, Illinois. His eldest son, Harvey, was 19 years old, born in Pennsylvania, and was also listed as a gunsmith. Six other children, ages 15; 13; 11; 9; 7; and 5, were all born in Ohio, although Smith seems to be unknown among Ohio collectors. He came to Fulton County, Illinois in about 1846. He was a farmer as well as a gunsmith, and his shop was on his farm. He was surprisingly prolific as a rifle maker and quite a number of his rifles are know here. All are fullstocks, two of my four were made without buttplates, three have brass trigger guards, but the fourth has a beautifully made hand-forged iron trigger guard. The rear sights look a lot like the one on this rifle, including the notch filed across the front. One of them has three punchmarks, forming a "V" at either end of the rear sight, just as you describe. Is the base of the front sight made of brass and staked in with four neat punch marks? All of the Samuel Smith rifles have very nice triggers and the rear trigger has an extremely deep crescent, like this rifle. Samuel Smith signed his rifles with a script "S. S.", and the picture of this signature certainly looks like it could be his, although it has enough wear that it's hard to say for sure. Samuel Smith died Sept. 4, 1872. I have copies of his estate inventory, which has a fairly extensive list of gunsmith's tools.
I should mention that there are also some differences. Three of my rifles have a bit more graceful architecture than this one, but the fourth one is similar. That one has a full patchbox, and I considered that to be the only reason it has a higher comb, but maybe not. Also, my Smith rifles all have a pronounced forward "hook" at the back of the trigger guard rail. This rifle is just the opposite, with the hook turning back. I have often thought that Samuel Smith's style continued to evolve a little through the years, so some details could easily differ .