Know Your Shot! – Maximum Point Blank Range
The Problem
The modern hunting rifle chambered in a flat-shooting cartridge is a highly effective tool for hunting big game. We can launch hunting bullets from most big-game cartridges at about 3,000 feet per second (fps). This results in fantastic downrange energy transfer to our target and very flat trajectory. So is faster better? In general, yes, but let’s explore point-blank range before deciding: What is your cartridge point blank range?
Basics
When a bullet leaves the muzzle of the rifle barrel it immediately begins to experience two unforgiving masters. The first is gravity, which inexorably pulls the unsupported bullet back toward the earth. The second is the frictional force of the atmosphere that works to slow the bullet. Anyway, as soon as the bullet leaves the muzzle, it begins to fall back to earth and it immediately slows down, and continues to slow down.
How do we use this simple information? The combination of bullet distance traveled over time and bullet drop over time, as a function of the bullets shape, starting speed, and atmospheric conditions, allows us to project the approximate trajectory or path of the bullet, at least for practical hunting ranges. Let’s consider the maximum point-blank range (PBR) of your cartridge/rifle. You must also learn your personal limitations so that you can make a judgment about the range of your ethical shot.
You must know these things, as you owe it to your game animal to be certain when you pull the trigger
A Little Math
If a barrel and a scope reticles were perfectly parallel, the bullet would start about 1.5 inches below the line-of-sight, and would drop from there, always remaining below the crosshairs; however, we force the scope and bullet path to intersect around 25 to 35 yards from the muzzle, and then the bullet will arc back down to cross the scope’s line-of-sight again, often between 150 and 250 yards. We can decide where we want that intersection to be. Generally, we don’t want the bullet to travel too far above or below the line-of-sight. The math allows us to shoot targets at say 100 yards and predict the path of the bullet and where it will intersect the line-of-sight again beyond 100 yards.
Your PBR starts with understanding your cartridge/rifle’s PBR. Let’s say you are using a 270 Winchester that pushes a 140 grain Nosler Accubond out of the muzzle at 2960 fps. To keep this simple, we will use “standard atmospheric conditions” with elevation of sea level (29.53” in Hg), 59 degrees Fahrenheit, and 78 percent relative humidity. Understand that higher elevation, higher temperature, and lower humidity all result in less wind friction and flatter trajectories. All of these things help us to mathematically predict the arc of the bullet as it travels down-range.
Deer as a Target
If our deer-sized game has a vitals area of 10 inches in diameter, the PBR theoretical would mean that the bullet cannot travel more than 5 inches above or below the line of sight. If you check out the numbers on JBM Ballistics, it would make our PBR 359 yards. Now, recognize that our rifle isn’t perfectly accurate. Most hunting rifles will shoot 1.0 to 1.5 inch groups at 100 yards. At 350 yards, the rifle’s group will open to 3.5 to 5.2 inches. This means we just lost a big portion of our 10-inch vitals area, and note that our bullet would be likely to be outside of our 5-inch plus/minus envelope for much of its flight!
Let’s check it all out at 300 yards. If I sight my rifle in for 2.6 inches high at 100 yards, the bullet will be a maximum of 3.0 inches above LOS at 150 yards, dead on at 250 yards, and 3.5 inches low at 300 yards. If I add the rifle “accuracy” in, I could be 4.13 inches high at 150 yards, +/- 1.9 inches at 250 yards, and 5.75 inches low at 300 yards. This is all shooting from a bench rest, remember. Clearly, this rifle’s maximum PBR is less than 300 yards on deer!
Field Accuracy
Let’s generously assume you are pretty steady in the field, and that you and your 1.0 or 1.5 MOA rifle have a proven track record of making 2.0 MOA shots from field rests. Then we can reapply my math for the 300 yard case. Here’s how it would break down using a field accuracy of 2.0 MOA as opposed to the example above of 1.5 MOA rifle accuracy. At 100 yards we still sight 2.6 inches high and can expect to be no worse than 3.6 inches high total. At 150 yards we would be 3.0 + 1.5 or 4.5 inches worst-case and 250 yards we would be +/- 2.5 inches.
Finally at 275 yards we will be at 1.6 +2.75 or 4.35 inches low at worst. What I mean to show you is you and your rifle combined, should be good to hold dead-on out to maybe 275 yards and still know you will hit the 10-inch vital zone without much problem, assuming you can accurately choose where the center of that 10-inch zone is!!
Point Blank Lessons Applied
So there is a real difference between layup range and maximum hunting PBR. For most of us, any shot beyond about 250 yards on a deer sized animal will take considerable concentration and effort, not to mention a very solid rest and a quality hunting rifle. The good news is you don’t have to worry about twisting any knobs or memorizing ballistic reticles out to about 275 yards on deer and probably closer to 300 to 320 yards on elk.
When I was a young man, I realized this whole PBR thing could really improve my no-guess range. I dutifully sighted my rifle in for 2.5 inches high at 100 yards. After a few years like this, I finally realized that this wasn’t for me. I strongly prefer to use a 1.8 to 2.0 inch high sighting at 100 yards which would keep that 270 at a maximum bullet path of 2.2 inches high at 125 yards and still 3.1 inches low at 275 yards. This limits my PBR to 270 yards or so, but the benefit is my trajectory in that range is quite a bit tighter, which I prefer, as most of my shots occur inside of 250 yards. Personal preference, but it comes from years of experience.
The important lessons here are really twofold. First, recognize the utility provided by PBR. This allows you to hold dead-center on your game inside of that range. It is a powerful hunting tool in the field. The second is to realize the detrimental effects that your own personal and rifle/cartridge limitations impose. This is why so many people seek rifle/loads that are capable of sub-MOA accuracy and very flat trajectories.
Refine Until the Concept is Useful
Try an exercise. With a flat-shooting, low-recoil cartridge (17HMR, .223, 22-250 etc.) set up a number of paper targets at 100 yards. Now shoot 5 rounds at each of four targets as follows. 1) from a prone position using a backpack as a rest; 2) from a standard “sitting” position; 3) from a sitting position with shooting sticks; and 4) from a standing position with shooting sticks. Be sure to let the barrel cool between shots for the centerfire cartridges (not so important with the 17 HMR).
Measure each of your groups across the widest spot. If your test rifle has similar inherent accuracy to your hunting rifle, you now have a pretty fair snapshot of your existing field level accuracy for each shooting position. For all intents and purposes, inches at 100 yards equals MOA (2.4 inch 100-yard group is a 2.4 MOA group that should be 4.8 inches…but still 2.4 MOA…at 200 yards). Now you have the data you need to decide what your actual maximum PBR is. More importantly, you now also have a decent idea just how far you can shoot from your most steady and stable resting position. Just be sure to confirm this test with your actual hunting rifle. Experienced hunters plan for shots and carry appropriate aids to stabilize their shooting rest.
Why?
Above all, it is your responsibility to know your limitations. This includes the limitations of your rifle, the loads you use in it, the weather conditions that affect you, your maximum PBR, and the effects of your shooting position and rest in the field. You must know these things, as you owe it to your game animal to be certain when you pull the trigger. A split second later a lethal bullet must enter their vitals and give a humane kill. If you can’t do this or commit to this, it is my opinion that you have no business hunting.
The good news is that careful and proper practice will bring your skill level up. This is where inexpensive rounds like .22 LR, .17HMR, and .223 shine when chambered in an accurate rifle. Mistakes are made and sometimes bad shots happen. They must not happen due to ignorance or your neglecting the risks associated with each shot. Knowing your maximum PBR and your own limitations is how you get there!!
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