When it comes to selecting cartridges for hunting the wide - open spaces, deer and pronghorn hunting have a lot in common. The key is selecting a cartridge that will shoot flat to assist in reaching out across those empty lands. To achieve that, the bullet should exit the rifle with a velocity at or very near 3,000 fps. It goes without saying that the bullet should have a streamlined shape and a high ballistic coefficient. It should also have good terminal ballistic qualities to ensure that it will expand well at the lower - impact velocity of long shots and still hold together on the closer hits where it’s going much faster.
You Need Enough Energy
The difference in critters is that big trophy deer, particularly mule deer, are much bigger and tougher than the most macho pronghorns that ever grazed the plains. The long - held standard of energy for deer hunting has been 1,000 foot - pounds (fp) delivered at the target. That’s acceptable for pronghorns and most deer. However, with today’s dwindling hunting opportunities and the limited time that most of us have to hunt, I would put the threshold higher for deer.
There seems to be more emphasis placed on trophy quality today than in generations past, and trophy bucks are different from their little brothers. These are the biggest, toughest deer in the herd. They know they are dominant and they act it; they fear little and feel inferior to nothing. They are at their peak of physical conditioning and have proven their dominance in battle. They have a tenacity to life that stretches beyond that of most other deer. It is always best to plan on the worst - case scenario with trophy bucks and to err a little on the side of more power. For these deer, I draw the bottom line at 1,500 fp delivered at the target.
I also think that a genuine 300 yards is a very long shot and is as far as most of us should consider shooting at game. I’ll allow a cushion for the recognition that most of us will stretch that now and again, particularly if the antlers or horns are big. So the cartridge must be able to deliver that energy to 400 yards.
The .200 Family, Plus 6 & 7mms
The only 6mm cartridge that honestly meets the 1,000 fp pronghorn requirement is the .240 Wthby Mag. Both the 6mm Rem. and the .243 Win. poop out early. If you absolutely keep your shots to less than 300 yards, they work, but will you?
The .25 - 06 Rem. makes the cut, but barely. The .257 Wthby Mag. does it a little better. The .260 Rem. will slide in, but only if long barrels are used and the factory - published ballistics are honest. My testing so far says they are not. The .264 Win. may be one of the finest pronghorn rifles ever conceived, but who uses one today? I don’t think any gun company is making them. The .264 is often called a belted .270 Win., and every gun company on earth makes rifles for this cartridge. With sleek 130 - grain bullets, it’s a great pronghorn cartridge. The .270 Wthby Mag. does it even better because it’s faster. The .270 Win. doesn’t make the cut for trophy deer, although it’s close. I expect I’ll take some nasty hits from .270 fans for pointing out its inadequacies, but the facts are inarguable. Based on factory specs, the .270 Wthby Mag. does it for deer with room to spare.
You might consider the 7mm - 08 Rem., but in this scenario I see little use for any short - action cartridge. Bullets heavy enough for hunting big game - that is, 140 grains or more - fall far short of 3,000 fps from any factory short - action cartridge and the guns commonly used to shoot them. So even if the energy is acceptable, the velocity is such that the trajectory arch is a little too big for good long - range shooting.
The .280 Rem. is a far better choice. It’s also just slipping into the domain of our long - range trophy deer cartridge. With the right loads and rifle, where a 140 - grain bullet is hitting an honest 3,000 fps, it carries our 1,500 fp energy threshold past 400 yards (although I have yet to see that velocity on my chronograph screen from a 140 - grain factory load fired from a .280 Rem. with a 22 - inch barrel). Some handloads will do it, but my personal solution was to have one of my .280 Rems. rechambered to .280 Ackley Improved. It now easily pushes a 140 - grain Nosler Ballistic Tip bullet to 3,100 fps from a 22 - inch barrel.
The 7mm Rem. Mag., 7mm Wthby Mag. and 7mm STW all do it nicely with bullets from 140 to 160 grains. They are excellent choices for deer or pronghorns. Remember that there is no such thing as overkill; you can’t make something too dead. The one constant in this style of hunting is the always - present possibility of a very long shot. The flatter a rifle cartridge will shoot, the better pronghorn or long - range deer gun it becomes. Flat trajectories always require high velocity. A by - product of high velocity with a hunting - weight bullet is energy. Energy grows exponentially to velocity, so the gains in energy are always larger than the increases in velocity. If a bullet that shoots flat delivers much more than the needed energy, so what? Dead is dead, but you’ve got to hit them first!
The .300 Family
The .308 Win. has that “short - action syndrome” mentioned earlier. It carries enough energy for pronghorns, but trajectories are a little arched. The .30 - 06 barely makes the cut for trophy deer. You must use a bullet with a high ballistic coefficient to hold the energy up. The hot factory loads with Nosler 165 - grain Ballistic Tip bullets or the Federal load with Sierra boattail bullets would be among my first choices.
The .300 magnums all are flat shooting and hard hitting. The .300 Win. Mag., .300 Wthby Mag. and even the big .300 Rem. Ultra Mag. and .30 - 378 Wthby Mag. will deliver a bullet with all our requirements. The downside is that excessive recoil is starting to rear its ugly head. Some shooters find that once the .30 caliber magnum threshold is crossed, recoil becomes hard to manage. It is far better to be honest with yourself and choose a rifle with slightly less power if you are recoil shy. The primary importance in any long - range hunting situation is that you be able to shoot the rifle well. On the other hand, if you are indeed able to shoot well, the magnums are all outstanding for long - range hunting.
Moving up from there is unnecessary. There are some bigger cartridges that will work - the .340 Wthby Mag., .338 - 378 Wthby, .338 Win. Mag. and Remington’s .338 Ultra Mag. all fit the bill. But they kick! Recoil starts to become a dominating factor with any shooter. Long - range hunting requires precision shooting, and it’s a very rare individual who can do his or her best with these cartridges from hunting - weight rifles. Besides, while it’s true that there is no such thing as overkill, there is a line of absurdity. For pronghorns and even deer, these big guns start to cross it.