So why do they sell centerfire ammunition with so many bullet weight options?
Most of us understand why they have frangible bullets for varmints, expanding bullets for deer, deep penetrating bullets for moose and grizzlies, and solids for elephants, but why polymer tipped, expanding deer bullets from 130-grain to 150-grain in the .270 Win? Or 150-grain,165-grain and 180-grain in .30-06? Which should we choose?
Choices depend on personal preferences, what shoots accurately in your rifle, and how far you wish/hope to fling them, but here are some basic rules to consider:
1. If bullets are roughly the same shape, i.e. same nose taper and point plus boat tail, the lighter one will start faster and fly flatter. The heavier one will deflect less in the wind and retain more energy downrange. Choose the lighter bullet if you want to shoot the flattest trajectory, the heaviest if you're concerned with wind deflection or retained energy.
2. Lighter bullets recoil less than heavy. Recoil is a product of total weight of the ejecta tempered by mass of the rifle. Since powder weight varies minimally between light and heavy bullets and your rifle's weight doesn't change, it is bullet weight that most changes recoil. Stick with light bullets for recoil sensitive shooters (within acceptable levels of expansion, penetration, retained energy, etc.)
3. Round and flat-nosed bullets, regardless of weight, drop more, deflect more in wind and lose more energy downrange than spire points. It's all about ballistic efficiency. Blunt bullets waste energy pushing air. Sleek bullets slip through it.
4. Extremely long, heavy bullets might not stabilize in standard rifling twists. Various cartridge/caliber rifling twist rates were established decades back when today's highest B.C., long bullets didn't exist. All copper bullets are longer than lead cores for equal weight and may not stabilize in slow-twist or even standard twist barrels. It's not the weight that matters, but the length.
5. Handloaders can really extend their bullet options. In .308 bullets, for instance, you can find them from 100-grains to 220 grains. The extremes might not shoot accurately in your rifle, so experiment. Sometimes extremely light, thin-jacketed bullets spin apart at high velocities. Long, heavy bullets often don't stabilize.
6. Consider bullet construction when increasing speed or reducing weight. How will the bullet react upon striking game? Monolithic bullets, bonded bullets and hybrids designed for controlled expansion and deep penetration, often perform (penetrate) much farther than traditional cup-and-core bullets, so you can get away with shooting lighter bullets than traditionally used.
Regardless which bullets you choose, practice shooting so you can deliver them exactly where they belong. The wrong bullet in the right place beats the right bullet in the wrong place every time.
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