Point-blank shooting: the concept of maximum point-blank range has great value to hunters.
The maximum point-blank range (MPBR) is the farthest distance at which the bullet stays within the vital zone, and the MPBR zero is the range at which you zero the gun to achieve the MPBR for size of the animal you're hunting. Properly done, the hunter aims at the center of the vital zone, and as long as the animal is not farther away than the MPBR, a well-executed shot will strike within that zone--you don't have to hold high or low.
The MPBR distance depends upon how flat your cartridge shoots and how large your quarry is. In general, high-velocity, small-caliber cartridges deliver longer MPBRs than do slower, big-bore cartridges. And it you're shooting at an elk, you've got a much larger vital-zone window than you do with a prairie dog.
To get the most utility from your particular gun and load, you need to sight it for the MPBR zero for the particular quarry you hunt. Consider the trajectory for a 55-grain .223 Rem. bullet with a muzzle velocity of about 3,600 fps. If you're shooting, say, groundhogs and have zeroed your rifle for 200 yards, the bullet would be within the four-inch critical zone (in other words, plus of minus two inches) from the muzzle out to about 250 yards. But if you increase the sight-in zero to 250 yards, the bullet then stays within the two-inch plus/minus range from the muzzle to about 290 yards--thereby increasing your MPBR distance by 15 percent.
How do you figure all this out? Well, you could use trial and error, combined with a lot of experience. Or if you have access to a long enough firing range, you can try a variety of zero distances until you discover the sweet spot.
Me, I live on a computer, so I just plug in the velocity and ballistic coefficient of my favorite load--plus the vital-zone diameter of my target--into a ballistic software program and Jet it figure it out for me. Programs such as Load From a Disk of RCBS Load will not only provide the MPBR zero point for your specific load and gun but will also tell you where the bullet impact for an MPBR zero should be at 100 yards--in case your target range doesn't go out far enough for you to actually zero at the optimum point. For example, with that .223 load discussed earlier, you could sight in your rifle to shoot 1.85 inches high at 100 yards to give you a 250-yard zero for a 290-yard MPBR.
You can also find that most of the comprehensive handloading manuals (the Sierra manual is particularly outstanding in this regard) include MPBR information, and the correct zero range to achieve it, in their ballistics table--for every bullet and every muzzle velocity level.
All of which explains why, when you ask a real rifleman, "How far should I zero my gun?" his answer should always be: "Depends on the gun, depends on the load, depends on the target."
Vital Zones (inches)
Moose: 18 Elk: 16 Mule Deer: 12 alaska Grizzly: 12 Caribou: 10 Pronghorn: 10 Whitetail: 10 Black Bear: 8 coyote: 5 Groundhog: 4 Prairie Dog: 3
RUGER. The elegant No. 1 in stainless/gray laminate trim is one of the most attractive rifles on the market, and now it's chambered to the zippy new .204 Ruger. The No. 1 Stainless Varminter's 26-inch heavy barrel will help hunters wring top velocity out of this hot little cartridge (advertised as a lightning-fast 4,225 fps). The gun is drilled and tapped for target blocks and comes with medium height, one-inch scope rings. Weight: 9.0 pounds. $950. 520/541-8820, WWW.RUGER-FIREARMS.COM
SAKO. One of the attractions of Sako rifles is their true action lengths, and this year the firm adds a fifth length: the Short Magnum. Designed around the .270 Win. Short Mag. and .300 WSM, this new action length will maximize the efficiency and accuracy of these newly popular cartridges. The 75 Hunter is the classiest of the 75 series with its high-gloss walnut stock, distinctive checkering and tasteful blue finish (stainless synthetic and Finnlight versions also now available in this action length). $1,163. 301/283-2191, WWW.BERETTAUSA.COM
BROWNING. A camo look is only one aspect of the new A-Bolt. The titanium receiver and composite/steel insert barrel make it extremely light weight. The fiberglass Bell and Carlson stock is finished in Mossy Oak New Break-Up and adds Dura-Touch armor coating for a secure grip. It's fitted with Pachmayr Decelerator pad and chambered to all three Winchester Short Magnums. Weight: 5.5 pounds. 801/876-2711, www.BROWNING.COM
REMINGTON. The Model 700 has never strayed far from its roots, and the new Classic Deluxe version incorporates a few welcome touches: a cheekpiece on the satin-finished, straight-comb stock and a 24-inch barrel (26-inch on magnums). The black fore-end tip and grip cap and a jeweled bolt body enhance the classic styling. Hinged floorplate magazine holds four standard rounds or three magnums. Available in short, long and magnum actions in eight calibers ranging from .243 Win. to .300 Ultra Mag. Weight: 7.375 to 7.625 pounds. $709 to $749. 800/243-9700, WWW.REMINGTON.COM
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|Title Annotation:||Centerfire Rifle Guide|
|Date:||May 1, 2004|
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