Often, we hear the term that hunting is not “rocket science.” But that, quite frankly is not actually true. A hunter who understands the capability of his/her rifle and ammunition combination can be a more successful and ethical hunter in the elk woods. Ballistics is the term used to define the mechanical performance of a projectile. Bullet manufacturers publish these performance data points in terms of energy (foot-pounds), velocity (feet per second), and trajectory (rise or drop measured in inches) for each grain and caliber of bullet they sell. The hunter can use these numbers to assess which one is best for their hunt. Everyone has heard or told stories as to which caliber is the best for this species or that species. Sitting around the campfire many boastful comments have been made, such as “this gun dropped that elk with one shot,” or “this gun is fast and flat-shooting but doesn’t have the knock-down power.” From a physics point of view, “knock-down power” is the energy or more specifically kinetic energy and “fast and flat-shooting” is the velocity and trajectory of the bullet.
Another data point manufacturers will provide is the ballistics coefficient (BC). This number can also be thought of as the coefficient of drag. Mechanically, this is similar to the wind resistance a car experiences driving down the highway. A higher coefficient means less drag and a lower number is more drag. A bullet with a high BC is more aerodynamically efficient and will hold a flatter trajectory than a bullet with a low BC. Some manufactures sell bullets with plastic tips to improve the BC. Figure1 shows the difference between a plastic tipped bullet and a more traditional bullet tip. For example, Figure 1 shows a Remington .30-06 150 grain Core Lokt PSP bullet has a BC of .314 (bullet on the left) where as a Remington .30-06 180 grain Scirocco has a BC of .500 (bullet on the right).
The tradeoff of a plastic tipped bullet is that it may not expand as immediately on impact or as quickly as a more traditional blunt tipped bullet. Most bullets will expand two to three times their original diameter. This expansion or “mushrooming” of the bullet is a function of impact velocity and bullet construction. Arguably, the minimum impact velocity for bullet expansion is 1500 ft/s to 2000 ft/s. Knowing the minimum impact velocity needed for proper expansion will help the hunter determine the maximum effective range for the caliber and bullet they choose. Manufacturers don’t quantify expansion for each bullet they produce. Bullet expansion and penetration, also known as terminal ballistics, is the advanced study of a projectile when it hits a target and is beyond the scope of this article. Ballistic experts will use ballistics gel to study the terminal performance of bullets. At some point in the future, ballistic experts may create standard terminal ballistics metrics to compare and contrast the different bullets manufactured.
However, if we simply compare the sectional area or major diameter of a .243 Win. and a .30-06, the .30 caliber bullet will have 25 percent more sectional area than the .243 Win. Unless you are an expert marksman, 25 percent is a generous amount of tolerance to help the average shooter make a one-shot kill.
Not every hunter is going to have the math skills or the time to calculate the energy or plot the bullet trajectory to compare and contrast which rifle caliber and ammo combination is best for their elk hunt. Today, most manufacturers provide free online downloadable ballistic calculators which can give exact energy, velocity, and trajectory values for specific ranges and calibers. Some rifle scope manufacturers will have similar online calculators for download. Two simple favorites include Remington’s “Shoot!” (Figure 2 & 3) and Nikon’s “Spot On” (Figure 4).
Scope manufacturers will highlight their bullet compensating reticle designs. Some scope reticles offer elevation gradations known as "mil dots," which is a nice feature that I’d recommend. However, the hunter still has to correctly range the target. A good laser range-finder should be part of your hunting pack.
Unfortunately, not all elk are going to stand broadside at 100 yards and wait for you to precisely line up a shot to its vitals. If we examine the ballistics data for a 400-yard or longer shot, the bullet trajectory starts to become a significant factor. For some calibers, the bullet will drop 2 feet from a 200-yard zero. It takes a skilled shooter to consistently make shots beyond 400 yards. An ethical hunter clearly understands his or her capability and refrains from attempting shots that are beyond the effective range of the hunter and the firearm. Various scopes, laser range finders, and angle-compensating devices all help in making the mid- to long-range one shot, one kill a reality.
A simple tool to aid the hunter is to tape a small drop chart (Figure5) somewhere on your rifle. A good drop chart will detail the range of each mil dot or elevation graduation of your rifle scope. By using the online tools and some practice shooting at your local rifle range, you’ll be better prepared for that mid- to long-range shot on a bull of a lifetime.
A commonly accepted threshold for the minimum amount of kinetic energy needed to kill an elk is 1500 ft-lbs. For whitetail deer, the minimum amount of kinetic energy is 1000 ft-lbs. We’ve all probably heard stories of hunters taking elk with a .243 Win. If you use the 1500 ft-lb rule of thumb and Remington’s Shoot software you could conclude that elk can be taken with a .243 Win. at 100 yards. But is this really the most ethical caliber to use? If the elk was standing broadside at 300 yards, the .243 Win. Remington 100 grain Core Lokt PSP would only have the minimum energy (1089 ft-lb) to take down a whitetail. The elk could run off wounded and be left to suffer.
Colorado elk are often found in very rugged terrain. A mortally wounded elk can still go over a 10,000-foot ridgeline that it may take the hunter a solid hour to get over on foot. A lightly wounded elk can cover the mile or two between you and the next valley in a couple of minutes. Another complication is the access in elk country may not be the same as in whitetail country. In whitetail country, a 10-minute ATV ride may be all that’s required to find a wounded whitetail, whereas in the vastness of Colorado the elk is gone.
A big part of being an ethical hunter means treating the elk with respect. One way to do that is by making a quick clean kill. Also, it’ll be easier on you the hunter when it comes time to pack out the meat if the elk falls where the bullet hits him. A downed elk is significantly more work cleaning and quartering than a whitetail deer. Whitetail can be somewhat “muscled” around where as a 600-pound elk will require some additional hands-on time. As the saying goes, “Once the elk is down, the real work begins.”
Rather than betting on a .243 Win., a wiser scenario would be to take a 30.06 into the field. At 300-yards, a .30-06 180 grain Remington Core Lokt PSP will deliver 1666 ft-lbs of energy, more than enough for a broadside shot. So if terminal energy is the game, why wouldn’t we recommend you choose the largest most powerful rifle caliber manufactured? For example, the .300 Remington Ultra Magnum shooting a 180 grain bullet will deliver 1500 ft-lb of kinetic energy at 744 yards. Is more always better?
Ultra-magnum rifles do have a lot of power, but they also have a lot of felt recoil. So, it comes down to how much recoil a hunter can handle and still make an accurate shot—and consistently make an accurate shot. A well-placed bullet will put more elk meat in your freezer than a poorly placed bullet from the biggest, baddest rifle around. See EHU 101
Lesson 12 - Guns, Gear, & Stuff for data on recoil energy for different caliber rifles.
As you start to look through the ballistics data for different calibers, bullets, and manufactures, you’ll notice that there are a lot of options and choices. In the end, the one option every hunter needs to have is confidence in their gun, optics, ammunition, and to know their own limits. Whether it’s ranging the target, making a mid-range quartering shot, or gaining the physical endurance to get into place and make a skilled shot at 10,000 feet above sea level, a successful elk hunter has to master a host of challenges. I hope this article has given you some useful information to help you choose a caliber and bullet that you will feel confident taking into the field. Enjoy the season and good luck!
Appendix: Credits and Author recommended websites
V-Max is a trademark of Hornady Manufacturing Company
Thanks to Shannon Sabata and Everett Deger for their consent.
Hornady Manufacturing Company
3625 West Old Potash Hwy Grand Island, NE 68803
Remington .30-06 165 grain Core Lokt PSP Remington .30-06 180 grain Scirocco. Photo by Gerry Sherman
Figure 2 & 3
Core-Lokt PSP is a trademark of RA Brands, L.L.C., Madison, NC 27025.
Scirocco is a trademark of Swift Bullet Co.
Figure 4 & 5
Nikon and Spot On are trademarks of Nikon Corporation.
Thanks to Kelly for their consent.
Nikon Binoculars and Scopes
(The mention of products, services, and websites in this article does not constitute expressed or implied endorsement by Colorado Parks and Wildlife.)