speaking of bullet selection, what are the intended purposes for all the grain selections?
308 can go from 120 grain to 200.
what works best for medium game like whitetail and hogs? and what would work well for larger game if the opportunity were to ever arrise?
What a bullet is for depends on the construction of the bullet and intended purpose as well as the weight. Some bullets fragment or expand a lot, creating a large hole. Other bullets are bonded and have controlled expansion so they create a smaller hole but penetrate deeper. Some bullets are solid copper and they retain all their weight and penetrate deep.
A lighter bullet will generally go faster and create more shock, but it will generally penetrate less. A heavier bullet is slower but has more mass, so it will *generally* penetrate deeper but it will create less destruction along its path.
For deer and hogs, any bullet that expands and is designed for hunting should do. Most people would recommend a 150 or 165gr bullet from what I have read. I have seen 150 and 165gr work well on deer.
For very large game people generally recommend the bonded bullets designed to break large bones and penetrate deeper, and usually a heavier bullet but it depends on bullet construction. If you do an internet search for ".308 bullet Elk" or similar you will find many discussions on which bullets are tougher.