Good job Morgan! That will make you a nice little bow for sure. Ive not had the chance to work my hackberry yet but I tend to work white wood in the winter months.
When you say toast the belly, it should be just that, make that dude look like a nice piece of dark brown toast. But in the same manner take your time doing it. If you hold your heat gun closer than about 6 inches from the belly you are just darkening the surface. If you hold it back and it takes some time to get dark then you are doing it right. It should take about a half hour to 45 min per limb to do a heat treat. Try that on your next one, you will see a big difference.
Another small pointer on your leather handle. Looks like you used either bow string or possibly artificial sinew to sew it together. Instead of punching holes with a leather punch try using a drill with a very small drill bit or a small nail. That will give you a tighter fit and a strong seam. But thats just aesthetics. But hey, thats why we are here, to share our work and learn from each other!
Patrick