Bow maker here; I shaped the two stocks on the guns I built from a plank with a US made #49 cabinet maker's rasp, I use the same for shaping osage bows. I started trimming the corners with my band saw and saw how quickly I could screw up (first gun) and went back to my rasp.
Hobbyists like me never get in a hurry, I don't remember exactly but it probably took me 2 hours to go from a wide, square blank to a mostly shaped buttstock, the forearm went much quicker.