The rifle most probably was made by Joseph Haberstro. He worked earlier in Buffalo, 1832-1844, and used curly maple frequently, while Robson was a late maker ca. 1850-1851 in Buffalo making primarily walnut half-stocked NY style rifles. I'd date this rifle to about 1835-1840, too early for Robson. Haberstro also used a rear pipe with a short, pointed rear flange as seen on this rifle, an identical lock bolt washer and butt plate, and double rings/bands at ends of his pipes as seen here. It sure looks like a Haberstro rifle to me. Shelby Gallien