|
Practical Performance of Popular Rifle Cartridges By Gary Zinn  Two articles recently posted on Guns and Shooting Online coalesced my thinking about something that I had been pondering for awhile. The articles, both by Chuck Hawks, were The 10 Best Selling Centerfire Cartridges in the USA and The Personal Range Limit. The first article prompted me to wonder, "What are the practical/realistic range and performance limitations of the most popular cartridges?" The second article raised the question, "How do the abilities of a hunter, under field conditions, jibe with the performance limits of the firearm used?" These questions are best addressed in sequence. Accordingly, I organized some basic data about the cartridges in question and did key calculations on their range and terminal performance. This serves as a framework for subsequent discussion of the "personal range limit" concept. The 10 Best Selling Cartridges article listed the most popular centerfire rifle cartridges, based on 2015 cartridge and loading die sales and other relevant data. Three honorable mention cartridges were noted and I added five more that I personally feel should be much more popular than they are, or which have a firm niche position in the world of modern rifle cartridges. The top ten are identified by number (in parenthesis), the honorable mentions with a (H) notation and my add-ons by an (A) notation. These 18 cartridges, with a selected hunting bullet and typical muzzle velocity (MV), are listed below, with the ballistic coefficient (BC) and sectional density (SD) of each bullet. Cartridge and load specifications
(1) .223 Remington: 50 gr. Sie. Blitz, MV 3325 f.p.s.; BC .222, SD .142 The first two cartridges are varmint getters, of course, as are the lighter bullet weights for the .243 Winchester and .257 Roberts. I increased the bullet weight for each successive cartridge, under the logic of heavier bullets being more resistant to wind drift at long ranges. The 100 grain .243 Winchester and 120 grain .257 Roberts loads are offered as Class 2 game loads. Whenever I have the opportunity, I keep reminding readers that the .257 Roberts cartridge refuses to die and should get more attention than it does.
(A) .25-06 Rem.: 117 gr. Sie. GameKing BTSP, MV 3030 f.p.s.; BC .410, SD . 253 The top ten ranked cartridges in this group are no-brainers, except that I did not expect to see the 7.62x39mm make the grade. I guess there is a lot of 7.62x39 blasting in semi-automatic rifles. The 7mm-08 Remington has slowly come to be more appreciated and it is good to see it within sight of the top ten. I added the .25-06 Remington, because it is reasonably popular and represents about as much ballistic performance as can be had in a .257 bore. The .280 Remington has proponents who claim it is better than the .270 Winchester. (Either way, the difference is slight.) The .260 Remington is included to represent the increasingly popular .264 bore niche, including the 6.5x55mm SE and the new 6.5 Creedmoor. The ballistic performance of these three calibers is virtually identical (depending on how they are loaded). Turning to the .308 caliber, I listed two bullet weights each for the .30-30, .308 Winchester and .30-06. The first .30-30 load is with the traditional 150-grain flat point bullet that has taken countless deer and other critters during a span of well over a century. The second is the recent Hornady LeverEvolution .30-30 load, which with a 160 grain Hornady FTX bullet and advanced propellent maximizes the ballistic performance of the cartridge. The first load for the .308 Winchester is with a 150-grain spitzer bullet. I judge this to be a natural load for the cartridge and it is what I use exclusively in my .308 deer rifle. I also listed a 165-grain load, because I feel the .308 handles it well for situations where a bit more sectional density and downrange energy are desired. I included the 165-grain bullet load for the .30-06 as a relatively light (for the cartridge) all-purpose load. The 180-grain load, though, is what made the .30-06 the legend it is today. A sturdy 180-grain bullet fired from a .30-06 has taken almost all big game animals, some of them pretty big, tough and in some cases dangerous. Finally, here are the most popular magnum cartridges, plus a sleeper that I sneaked in to keep the .338 Winchester Magnum company. I am not a big proponent of magnum rifle cartridges, but then I am strictly a whitetail deer hunter and will argue that magnums are unnecessary for deer and other Class 2 game. For the bigger and tougher Class 3 beasts, especially at long range, the magnums listed here make sense.
(7) 7mm Rem. Mag.: 150 gr. Sie. GameKing BTSP, MV 3110 f.p.s.; BC .436, SD .266 My sleeper is the .338 Federal. I did not get excited about this cartridge at first, but the more I study it the more impressive it is, at least on paper. The ballistics data show that the .338 Federal, with bullet weights between 185 and 210 grains, gets a lot of performance out of a necked-up .308 Winchester case. Elk, Moose and similar size game should take warning. Practical shooting distance limitations: Maximum Point Blank Range My point of departure for determining practical shooting distances is maximum point blank range (MPBR). For many years, I have used MPBR as a guide for sighting in my centerfire rifles, using a +/- 1-1/2 inches (3 inch target diameter) MPBR for varmint cartridges and +/- 3 inches (6 inch target diameter) for my deer rifles. This means that my absolute shooting range limit is wherever particular loads fired from a rifle, properly sighted in, will fall 1-1/2 inches or 3 inches below the line of sight for varmint or deer rifles, respectively. MPBR sets the outer limit of shooting distance for a practical hunter and is technically easy to apply in the field. Chuck Hawks explains this very well in The Personal Range Limit: "Forget about bullet drop tables, ballistic scope reticles and so forth. In fact, in the field, forget about long range shooting entirely. Zero your rifle for the +/- 3 inch maximum point blank range (MPBR) of the cartridge/load you are using and NEVER attempt a shot beyond that distance." Here are the four varmint cartridges and loads listed above, arranged in ascending order of their MPBRs. Retained energy (RE) at the 25 yard increment nearest to each MPBR is also shown. Finally, the far zero (FZ) of each load is noted, in parentheses; FZ will be discussed later.
With heavier weight bullets in each successive cartridge, the maximum +/- 1-1/2 inch MPBRs in this case all fall within 231 to 250 yards. This does not mean that these cartridges are not capable of being effective for varmint hunting at even longer ranges, for all have retained energy sufficient to upset varmint bullets well beyond 250 yards. I use the MPBR values as an unambiguous way of measuring the practical range of these cartridges. Cartridges and loads suited to CXP2 or larger game naturally fall into three +/- 3 inch MPBR groups. The first group is the smallest.
I think of the two cartridges and three loads in this first group as adequate for hunting deer and other Class 2 game. MPBRs are not greatly beyond 200 yards and the RE values are relatively low, especially for the 150-grain .30-30 and 7.62x39mm loads. (These two are not a similar as they appear here, as the far superior sectional density of the 150 grain .30-30 bullet make it a much more effective killer, especially on larger animals. -Editor) The next group of cartridges includes seven workhorse calibers and nine loads in total.
Who knew that so many capable cartridges and loads would fall within a 14 yard MPBR range? There are some other surprises here, too. The ones that caught my attention are that the 140-grain 7mm-08 Remington is the longest FZ cartridge in the group and the .243 Winchester is next. The workhorse .308 Winchester and .30-06 loads also nest comfortably in this group. Retained energy values are all adequate for Class 2 game and the 180-grain .30-06, 200-grain .338 Federal, and 210 grain .338 Winchester Magnum loads are definitely Class 3 capable with the right bullets. Another thing that the list above shows is that different bullet weights in the same cartridge get similar MPBRs, as long as the difference in bullet weights is not large. This is illustrated by the .308 Winchester and .30-06 data. In both cases, a 15-grain change in bullet weight results in a change in MPBR of only five yards. Now for the truly long reach cartridges and loads.
Like the previous group, these cartridges and loads fall within a 14 yard MPBR range. The magnum cartridges and loads should not be a surprise, but the non-magnum cartridges, especially the .260 Remington, might be. That a short action cartridge has such range is eye opening, except to those of us who have first-hand experience with the cartridge. Across the board, retained energy values are more than adequate for any game animal at which one might sanely shoot with these calibers and loads. Far Zero as an alternative practical shooting distance limitation I use Far Zero as an alternative, more conservative, practical shooting limit for hunting deer. Far zero is the range at which a bullet crosses the line of sight on its downward trajectory. The reason I suggest far zero as a shooting limit is the likelihood of making errors in visual range estimation in the field. (Which is a good argument for using an optical range finding instrument, whenever one has the time to do so.) The issue here is underestimating range. Suppose a hunter has a rifle and load sighted in for a +/- 3 inch MPBR of 265 yards and that he/she shoots at a deer at that range. If the shot is aimed at the center of the vital area and is executed flawlessly, then it will hit 3 inches lower than the aiming point, but still in the vitals. A good result. However, suppose the hunter underestimates the range by 40 yards, so that what is believed to be 265 yards is actually 305 yards. The shot will miss low (best result) or will hit the lower belly or a leg (tragic result). Suppose the far zero of the load being shot is 225 yards and the hunter believes a deer is at that range. If the actual range is again underestimated by 40 yards, the deer will actually be at 265 yards. However, this is not a problem, because a well-executed shot will hit the deer, just as would a correctly estimated 265 yard shot. If the range is overestimated the result is not problematical. The target, being closer than estimated, will be well within the MPBR or far zero distance, whichever is being used as a shooting distance limit. The far zero (FZ) ranges for the cartridges and loads used for this article are noted in parentheses in the group lists above. Here is a summary relating FZ to MPBR for each group. The four varmint loads have an average FZ of 210 yards, which is 33 yards less than their average MPBR. It can be generalized that one could underestimate the range of a varmint by up to 33 yards, but still make a good hit with a rifle sighted in for a +/- 1-1/2 inch MPBR. The average FZ of the .30-30 and 7.62x39 loads is 189 yards and the average MPBR is 221 yards, yielding an underestimation cushion of 32 yards. The average FZ range of the workhorse loads, .308 Winchester through 7mm-08 Remington, is 231 yards, compared with an average MPBR of 271 yards. The average underestimation cushion is 40 yards. The long reach loads, .260 Remington through 7mm Remington Magnum, have an average FZ of 252 yards and an average MPBR of 295 yards, yielding a range underestimation cushion of 43 yards. Lest anyone think this is all a paper exercise, let me share a personal example. My main deer rifle is a Winchester Model 70 Lightweight Carbine in .308 Winchester. The load I use is a 150-grain soft point spitzer bullet, rated at 2820 f.p.s. MV in a 24 inch barrel. My rifle has a 20 inch barrel, so a more realistic estimate of MV is 2740 f.p.s. The ballistic coefficient of my 150-grain .308 hunting bullets is 0.340. Plugging these BC and MV values, along with a 6 inch diameter target size, into a MPBR calculator (shooterscalculator.com), I get a FZ of 223 yards and a MPBR of 262 yards for this load in my rifle. If I restrict my shooting distance to no more than an estimated 223 yards, I have a 39 yard margin of error for range underestimation. I am actually even a bit more conservative than this, in that I have not taken many shots at deer at ranges beyond 200 yards. When I take long shots, they are under conditions of good light, a completely clear line of sight and a calm, stationary animal. Plus I rest my rifle solidly, by one means or another, and make sure that everything is "just so" before I squeeze the trigger. I have totally missed a few of these long shots, gotten a few deer and, most importantly, never made a crippling hit that resulted in losing an animal. I am good with those outcomes. The 9-inch paper plate personal range limit In a recent article discussing the difference between long range shooting and long hunting shots, hunting writer Craig Boddington observed that, "There are no shooting benches in the woods." His point is whatever groups one is capable of shooting from the bench are largely irrelevant when a nice buck suddenly appears across yonder field. What counts then is whether a steady, accurate shot can be executed from the best available position: using an impromptu rest (branch, stump, rock, etc.), sitting, or offhand (standing without anything to support and steady the rifle). The shooting positions just mentioned are doubtless the ones most used by hunters in the field. They are all effective (with practice), although the offhand position is the least accurate, especially as the range increases. Sitting is probably the most versatile and accurate position for most hunters. No less an authority than Jack O'Connor summed this up in the simple statement, "Sit and you'll hit." Support for a standing shot may be provided by a handy tree or fencepost, but today many hunters use a bipod, tripod, or shooting sticks. (Monopods are largely useless). I prefer a bipod, such as the Bog-Pod CLD-2, with legs that can be adjusted for use from either a sitting or standing position. My vote for the most stable field shooting position goes to the sitting position with the rifle forearm resting on a bipod. What about the prone and kneeling positions? Unfortunately, the inherently steady prone position is seldom useful in hunting. As Chuck Hawks points out, "The prone position is seldom viable in the field, because the hunter's head is too low to see over tall grass, low brush and other clutter." I cannot recall exactly how many times I have shot from the prone position in a lifetime of hunting, but I know the number is quite small. The kneeling position sucks. It is not particularly stable and one cannot maneuver the rifle. I see pictures of shooters taking kneeling positions in shooting magazines, but that is all the position is good for: photo ops. If kneeling is a position of prayer, then kneeling shots are shooting and praying. Here is a paraphrase from The Personal Range Limit: Whatever distance you can keep all of your shots on a nine inch paper plate when shooting from a sitting, standing, or prone position, without a single miss in at least 10 rounds, is your personal range limit from that position. It should be clear from the wording of this statement that the personal range limit likely will be different from the different shooting positions. Someone who is able to repeatedly drill the plate at 200 yards while sitting may only be able to make 160 yards with a supported standing position and 100 yards offhand. That is the whole point of the paper plate rule. Get away from the bench and see what are your personal range limits from actual shooting positions you will likely use in the field. Putting it all together in the field Here is a summary rendition of one of my deer hunts several years ago. I share this story because it illustrates the application of the things I have discussed. I was hunting a farm where there was a pasture field running along a ridge, with brush and woods on either side. There was a hay feeding frame near the west end of the field, but the cattle were elsewhere that day. I had scouted the area and knew that deer were active around this pasture. A gentle westerly breeze was blowing along the length of the field, so I decided to set up at the east end of the field and watch it for a while. I found a tree that I could sit against and from which I could clearly see across the length of the field. My optical rangefinder indicated that it was 180 yards to the hay feeder. This was excellent, for the rifle and load I was using had a MPBR of 262 yards and a FZ of 223 yards. Further, I knew that I could easily hit that 9 inch pie plate at 200 yards, from a sitting position, steadying the rifle on a field bipod. I cleared debris from where I wanted to sit and plant my feet, sat down and adjusted my bipod to pan the pasture. I then settled in to wait and watch. An hour later, a well-fed doe wandered into the field and ambled toward the hay feeder. I had an antlerless tag and some room in the freezer, so I got the deer in the scope, waited until she turned broadside, aimed at the center of the vital area and touched off the shot. I field dressed the deer and then hiked out to borrow a four wheeler to haul her in. Three steps to success There are three distinct things that must be done to implement the MPBR / FZ / 9 inch pie plate system. I will summarize them, making the exercise interesting by assuming that I have just mounted a new scope on my .308 Winchester deer rifle. Step 1 - Do the key calculations: The starting point is the load with which I plan to hunt. This will be a 150-grain soft point bullet, fired at 2820 f.p.s. MV from a 24 inch barrel. I adjust this MV for the 20 inch barrel on my rifle, so my adjusted MV is 2740 f.p.s. (See The Rifle Barrel for estimated barrel length adjustment factors.) Now, I need to determine the MPBR of this load, along with other key data for sighting in my rifle. Using the Point Blank Range calculator on shooterscalculator.com, I input the BC of the bullet (0.340), the initial velocity of the load (2740 f.p.s.) and the target size (6 inches) to calculate a +/- 3\'94 MPBR for this hunting load. Clicking on the Calculate button gives me the following outputs, which I need to go on to Step 2.
Step 2 - Go to the bench: I am ready to go to the range and sight in my rifle on a bench rest. My first step will be to bore sight the new scope. Very conveniently, the near zero for my load is 24 yards, so I would bore sight the scope on the 25-yard target board at my range. Once that is done, I would load up and shoot enough rounds at that distance to get the scope dialed in. Now I am ready to do the conventional 100 yard sight-in. The point blank range calculator indicated that my load should be sighted 2.75 inches high at 100 yards to get a +/- 3 inch MPBR of 262 yards. I will shoot and adjust the scope at 100 yards until I am satisfied that I have done this. I am ready now to move on to step 3, if I trust the numbers. However, I am going to be OCD and check where my bullets are hitting at 200 yards. For this, I will need an additional piece of data from the Ballistic Trajectory calculator on the Shooters Calculator site. Inputting the needed data, I found that the load I am using should be hitting 1.32 inches high at 200 yards. With this number in hand, I can shoot some groups at that range and tweak the zero, if necessary. Step 3 - Break out the paper plates: Now it is time to leave the bench and determine at what ranges I can hit those 9 inch paper plates, every time, from realistic field shooting positions. The ones I would include would be sitting with a bipod support, sitting with no additional support, standing with a bipod support and offhand (standing with no additional support except a "hasty sling" wrap on the off arm and wrist). The ranges at which I can always hit the plates from each position are my ultimate practical range limits. As an aside, I do not bother with shooting plates from the prone position, because I am so unlikely to actually use it. If the occasion arises, I am confident that I can accurately shoot from prone as far as I can from a supported sitting position. Conclusion Two more points from The Personal Range Limit article sum it up well: "One does not need to be able to master extreme conditions or long ranges to be a successful and ethical hunter. One can simply NOT shoot and wait for a better opportunity later, or on a future hunt. The thing is to shoot at live game within your capabilities and skill level and pass on any shot you don't absolutely KNOW you can make. If you THINK you can make a one shot kill, you may only wound. Superlative skill with a rifle or handgun is not required for enjoyable and rewarding big game hunting, but good judgment is." Exercising this good judgment requires understanding the practical and realistic capabilities of your firearm. Knowing the maximum point blank and far zero ranges of your rifle and load tell you this. Ultimately, though, any firearm is no more accurate than the person pulling the trigger. The ranges at which you can always hit the vital area of a game animal, using various shooting positions, define your practical and realistic capabilities as a shooter. I would be honored to share a hunt with anyone who knows and works within these personal capabilities, because that is the kind of person who is a truly responsible hunter. |
