How To Shop For Caliber, Cartridge and Bullet

Ron Spomer |

30-06_Caribou To simplify this, let’s just concentrate on calibers and cartridges here, because that’s ultimately what you’re picking. You can find all kinds of guns to fire the right cartridge.

First (you probably already know this, but bear with me for the new shooters), a caliber is just the diameter of the bore of bullet, and the bullet is always slightly larger than the bore. A 30-caliber is the bore size that spits a .308-caliber (.308-inch diameter) bullet. The 27-caliber shoots a .277” bullet, a .243-caliber handles bullets .24 of an inch across, etc. The bullets have to be slightly larger than the bore so they fill in the bottom of the rifling grooves. If they didn’t, powder gases would leak around the bullet and velocity would drop drastically.

A cartridge is the complete ammunition, a case fitted with a primer, filled with powder and capped with a bullet. Cartridge (case) shape determines which rifles it will function in properly. While a .30-30 Win., .308 Win., .30-06 Springfield, .300 Win. Mag. and .30-378 Weatherby are all 30 calibers firing .308-inch bullets, they cannot be used interchangeably due to the differing lengths, widths, tapers and shoulder angles of each case.

So, essentially a cartridge is just a convenient powder container that also holds the primer (external muzzleloader cap in the old days) and bullet. It’s shape doesn’t matter all that much, although gun nuts will argue this until the cows come home, get milked and return to pasture.

So, the longer and wider any cartridge case in any caliber, the more powder it will hold and the faster it will drive any bullet. Some smaller cases, like the .30-30, are not really efficient with heavy-for-caliber bullets. You’d want a bigger case like the .300 Win. Mag. to add good velocity to a 180-grain bullet, for instance.

The good news about calibers is that, with the right case and bullet, they can perform all out of proportion to their size. Today’s bullets and the wide selection of them insures you can get versatility out of many big game cartridges. The classic example of this is the old .30-06. It’s been loaded with bullet weights from 100-grains up to 220 grains, but most shooters now settle for weights from 125-grains to 180-grains in this cartridge.

As a general rule, bullets effective on game from the size of pronghorns to moose start at .24 or .25 caliber (hunters always argue this, but thousands of deer, elk, bears and moose have been taken with the little .243 Winchester) and go up to .375s. Most hunters opt for calibers and cartridges that are middle of the road. Three of the more popular calibers for deer-sized game are .27, .28 (also known as 7mm) and .30. You can’t go wrong with those. Choose one and your next step is to decide what case you want pushing it. The smaller the case, the lighter the recoil but slower the velocity. With any cartridge you can minimize recoil by shooting the smaller bullet sizes and by using a heavier rifle.

Most shooters can train themselves to handle the middle-of-the-road recoil of a .308 Win., .270 Win. or .30-06 in a 7- to 8-pound rifle, but if suspect you’re recoil sensitive, you might try a 7mm-08 Rem., 6.5 Creedmoor, .257 Roberts, .25-06 Rem. or .243 Win.

If you don’t mind recoil and desire extra speed, flatter trajectory and additional range, consider a .264 Win. Mag., 7mm Rem. Mag. or .300 Win. Mag. Just don’t fret excessively about the “perfect” deer or elk or big game rifle. They are extremely versatile with good bullet/ammo selection all can be made to perform beautifully.