American hunters have too many bullet choices. Do you buy the 87-grain or 100-grain or 115-grain or 117-grain or 120-grain bullet for your .25-06 Remington? Should you hunt whitetails with a 130-grain spire point in your .270 Winchester or 150-grain round nose?
Apart from concerns about accuracy and ballistic efficiency, bullet selection based on mass (weight) is fairly straightforward. The lightest bullets in any cartridge loaded to maximum velocity shoot fastest and flattest out to about 600 yards. The heavier models with the same basic shape (i.e. boat-tail spire point or flat-base spitzer, etc.) drop a bit more, but retain more energy downrange and deflect less in the wind. Because they retain more kinetic energy downrange and because their shanks are longer in relation to their diameter, they generally penetrate more deeply than their lighter cousins.
So, the easy answer is rather obvious: Use the lightest bullets in a given cartridge for the smaller game generally hunted with that cartridge. Use the heavier bullets for the biggest game conventionally hunted with that cartridge. Thus, a .270 Win. with 90-grain Sierra hollow points or 100-grain Hornady spire points would have good reach for long-range coyotes or chucks. A 130-grain Winchester Ballistic Silvertip or Swift Scirocco would be perfect for mule deer, and a 150-grain Nosler Partition, Federal Trophy Bonded Bear Claw or Barnes Triple Shock would be the go-to choice for elk or moose.
Beyond weights, however, one enters the realms of bullet shape (a big part of ballistic coefficient), materials and construction. These things radically change downrange trajectory and terminal performance. With the right mix of these, it’s possible for a 130-grain .270 bullet to outperform a specific 150-grain in trajectory, wind drift, punch and penetration. And that’s the real reason we have so many delightful (if confusing) choices in bullets.
The subject is worth diving into deeply (it’s not really “crap”) but to get your feet wet, just wade into the shallow end of the pond by using the lighter bullets for smaller game and flatter trajectory, the heavier bullets for bigger critters and less wind deflection. If those bullets—and you—shoot accurately, you’ll get your game.