Flatten The Curve for Hunting Deer – Part 2, by Behind The Counter

(Continued from Part 1. This concludes the article.)

The topics that I’ll deal with in Part 2 include:
• The size, shape, location, and contents of a deer’s vital zone,
• Legal, ethical, and practical considerations using your defense rifle for hunting,
• Other caliber options available for your AR-15 platform including .300 Blackout, 6.5 Grendel, 6.8 SPC, .224 Valkyrie, .22 Nosler, .350 Legend, and the new kid on the block 6mm ARC.

Let’s begin by understanding where to aim.


Well, it depends. A deer’s vital zone area is easy to visualize. Draw a horizontal line splitting the deer’s body. Draw a vertical line straight up the back of a deer’s front leg. The intersection is the center of the vital zone. This is where the lungs and all the major arteries and veins come together with the heart in the lower portion. For a small doe, the vital area is a circle 5” to 8” in diameter, and on a large buck, the circle might be as large as 10” to 11”. If you aim at the center of that circle, your shot should still be fatal 4” high or low on a small doe and 5” high or low on a big buck.

Berger Bullets, a premium bullet manufacturer offers free downloadable vital zone targets. Designed to print on standard size paper, these targets are a great way to lock in the visual image of your target as you practice. Using one of the images on the Berger target, I super-imposed the dotted red lines below – splitting the body in the middle and coming straight up the back of the front legs. The three irregular shapes on the target show the location of the vital zone. Where the two red lines cross is your aiming point. The Berger target will aid in visualization, but aiming at the unmarked center of a paper plate also works well. My personal preferences are an 8” round steel gong made from 3/8” thick AR500 steel and a similar 4” gong hanging from the same cross bar. Start at 100 yards on the 8” target. (The image is from atlastargetworks.com. After warming up and getting relaxed, put all your attention on the 4” steel target. Then, move the target set further away and continue to practice. Aim small.

A successful shot may not drop your quarry in its tracks. In fact, expect that it may take 10 seconds for death to occur, and a leaping deer will travel a fair distance in that short time. Depending on the actual shot placement, it may take a minute or more for the deer to bleed out. Sometimes, you do everything according to the book, but at the last second, the deer looks up or smells your scent or hears a twig snap or sees the white flag from another deer. A single step in that fraction of a second could cause your shot to be several inches off dead center. Maybe you got “buck fever” and jerked the shot a little. Perhaps at the very last fraction of a second, you flinched. If you have consistently practiced to hit the center of the vital zone, these last minute “gotchas” will probably not cause a complete miss. It just means more work to track the wounded deer.

MPBR also works for wind conditions up to 10 to 15 mph even at 90 degrees to your point of aim at ranges below 200 yards. Like bullet drop, the effect of wind drift increases dramatically with distance. It is also important to look for natural indications of wind speed and direction such as trees or grass near your target. The wind pattern might be quite different from where you are located. Depending on field conditions, you may need to adjust as much as the full size of the vital zone to compensate for the wind. Remember that your reference point is always the center of the vital zone. Once you have done all the basic work sighting in your rifle, practice some in windy conditions. That could be the real world on your hunt.


Assuming a 22-caliber centerfire cartridge is legal in your state, your personal defense weapon may be an excellent choice as your deer hunting rifle. Some states like Wyoming also specify an expanding bullet design and/or a 60 gr minimum weight. Two of the three gun stores closest to my shop had multiple choices for hunting loads in .223 Rem on the shelf. The third had only a few boxes of 55 gr FMJ rounds in 5.56. Your local conditions may leave no choice but the internet.

More to the point, is .223 / 5.56 an ethical choice? That depends on two key factors. Are you capable of consistently hitting a 4” steel gong at 100 yards from a variety of field positions? Yes, and we move to the next question. Whether your AR-15 is chambered for 5.56 or has a .223 Rem chamber, can your rifle and you put a 3-shot group on target with a maximum spread of 4” at 100 yards using factory .223 ammo? Yes? Keep practicing and enjoy your hunt!

If the answer is a qualified “Maybe…” or just plain “No.”, it may be time to do some detective work. Diagnosing the problem is something we have done for a number of customers. Sometimes the rifle needs a little help, for example a smoother and lighter trigger or clearer optics or just a more rigid scope mount. Sometimes the shooter needs to have someone coach with breathing, trigger squeeze, a more natural rifle fit, or better eye relief for the scope. Over the years, we have developed a routine process that works most of the time to get much tighter groups. That could be a topic for another article.


For the hunt my wife and I are planning this November, we concluded that her 5.56 AR would consistently put 3 shots of factory .223 hunting ammo in a 2” circle at 100 yards. With 5.56 handloads, her typical group size is smaller. She shoots well, picked out all the furniture on her rifle (buttstock, pistol grip, handguard, scope and mounts, trigger), and is familiar with the whole package. Between now and November, she will get plenty of practice time.

For my AR-15, I decided to take a completely different approach and look for a SAAMI (Sporting Arms and Ammunition Manufacturers Institute) approved cartridge that would function reliably in an AR platform and have terminal ballistics similar to a .243 Winchester.

What other cartridge options are readily available for the AR platform? My selection criteria were all based on practical, not tactical, considerations. I can be impressed that Special Forces or the Army Marksmanship Unit played a role in developing a particular cartridge, but the practical issues weigh more heavily.
• Is factory ammo readily available?
• Are the available bullets suitable for medium game or for putting holes in paper?
• Can I buy a complete upper receiver including the bolt as well as magazines?
• Does the new cartridge provide a clear performance edge over .223 or5.56?
If keeping track of new cartridges is not high on your list of important projects, let me recommend a truly excellent, comprehensive, no holds barred article that covers all of the SAAMI approved cartridges for the AR-15.

My takeaway from this article was that there were more good choices than I expected. My available options included Federal’s .224 Valkyrie, the .22 Nosler, the 6.8 Remington SPC, and the Winchester .350 Legend as well as the .300 Blackout in addition to the two cartridges that had immediately come to my mind for this project. My list had started with the 6.5 Grendel and 6mm ARC.

The ready availability of factory ammo especially in pandemic supply conditions was paramount. As bad as the current supply situation may be, it could get much worse over the next couple of years or in the blink of an eye. I was looking for a cartridge that might give me an edge in some way and had a legitimate chance to become a mainstream cartridge. The .300 Blackout is listed on the ammoseek.com website as outselling both the 6.5 Creedmoor and the .30-06 and just behind the .308. That is market acceptance! On the same list, the 6.5 Grendel is behind the .270 but outselling the .243 which is just ahead of the .30-30.



.223 Rem .300 Blackout 6.8 SPC .224 Valkyrie .22 Nosler .350 Legend 6.5 Grendel 6mm ARC
Barrel Length (inches) 16 16 16 18 18 18 18 18
Bullet Weight (gr) * 62 135 120 90 70 165 123 103
Ballistic Coefficient 0.310 0.274 0.400 0.424 0.370 0.250 0.510 0.512
Muzzle Velocity (fps) 2840 2085 2460 2620 2940 2180 2460 2680
Muzzle Energy (ft lbs) 1110 1303 1612 1372 1343 1741 1653 1643
Energy at 100 (yards) 925 1027 1387 1195 1155 1347 1460 1468
Drop at 200 yards (inches) -3.7 -8.7 -5.5 -4.3 -3.7 -8.0 -5.0 -3.9
Drift at 200 yards (inches) 3.7 6.6 3.5 3.0 2.9 6.9 2.7 2.4
Energy at 200 yards (ft lbs) 765 803 1188 1037 989 1030 1303 1308
Drop at 500 yards (inches) -58.4 128.8 73.4 62.4 49.7 123.5 67.7 55.4
Recoil (ft lbs) 3.8 6.1 8.0 5.9 5.3 10.4 8.7 7.7
max MPBR (yards) 231 174 210 224 248 201 214 232

We will discuss some of the key findings from this chart as we cover each of the cartridges. In all cases, we used a 100 yard zero for the ballistic curves. We assumed the rifle weight in each case was 7 lbs without optics and used several current reloading manuals to estimate the powder charges. The near zero for point blank range was generally about 25 yards and the height above dead center on the target at 100 yards was very close to 2 inches all across the board.

.300 Blackout (Advanced Armament / 55,000 psi / 2011)

My gun safe already includes the .300 Blackout in a 16” rifle version and a 9” pistol. For suppressed shooting at close ranges, this is a truly excellent round and continues to grow in popularity as a hunting cartridge. It has the enormous benefit of using the same bolt face as any .233/5.56 and the same magazines. None of the other cartridges approach its abilities for CQB (close quarter battle), but it is not competitive as a deer cartridge beyond 150 yards. In order to properly seat the heavy bullets used for subsonic loads, the case design required a reduced case capacity. That helps with the subsonic loads but limits the muzzle velocity with supersonic loads compared to all of the other cartridges. A further issue for me is that accuracy drops beyond 100 yards. OUT (short range)

6.8 Rem SPC (Remington + AMU / 55,000 psi / 2004)

I understood the reason for Remington’s collaboration with the Army Marksmanship Unit to create the 6.8 SPC. Out through 400 yards it easily meets its original design goals to improve on the lethality of the 5.56. Several excellent manufacturers make complete upper receivers, and I was able to find one supplier that had some in stock. What disqualified this cartridge for me were purely practical considerations plus the confusion caused by two SAAMI specs. The bolt has a larger bolt face to accommodate the larger rim size from the parent case. The bolt carrier and all of the other elements are the same as any standard AR. Ammo is relatively scarce, but factory hunting ammo is almost non-existent in today’s market. In fact, the 6.8 lags behind the .350 Legend, .450 Bushmaster, and even .458 SOCOM in ammo sales. Another factor was that none of my distributors had magazines in stock. OUT (mags, limited ammo)

Federal .224 Valkyrie (55,000 psi / 2018) and .22 Nosler (55,000 psi / 2017)

I was initially intrigued by Federal’s .224 Valkyrie as a way to take advantage of high ballistic coefficient bullets for long range varmint hunting and as a medium range choice with heavier bullets for deer and antelope. Both of these cartridges are superior to the .223/5.56 as you can see from the chart above. Because of the higher velocity with the 70 gr bullets, the Nosler outperforms the Valkyrie in the trajectory categories whereas the heavier 90 gr bullet with a high BC from the Val is better in all the energy categories. Because of its rebated rim, the Nosler uses the same bolt and bolt carrier group as a standard AR. Like the 6.8 SPC, the Val needs a bolt with a larger diameter face.

Unless you handload, the choice between the two might be dictated by the hunting loads available. Either one is a significantly more potent deer cartridge than the .223. The two new cartridges also fell out of consideration since they need the same unavailable magazines as the 6.8 SPC. They also have a very small market following, and the primary ammo manufacturers are Federal and Nosler. In fact, using Brownell’s, Midway USA, MidSouth, and Grafs as well as RSR, there were no complete upper receivers in stock in either cartridge and only one complete rifle in .224 Val. OUT and OUT (mags, limited receiver options, limited ammo)

.350 Legend (Winchester / 55,000 psi / 2019)

In states that limit deer hunting to cartridges with straight wall cases, this is a very solid choice, but it lags behind the .22 Nosler and .224 Valkyrie in all longer range performance categories related to muzzle velocity or energy. Although the case looks very similar to the .223/5.56, it is a totally new case that does not feed well from standard AR-15 magazines. Several manufacturers make magazines to accommodate the differences. This cartridge was designed to use a standard bolt face and bolt carrier group. My internet search turned up several available upper receivers. Interesting note – the .350 Legend was #15 on the ammoseek list – just behind the .30-30 and ahead of the 7mm Rem Mag. OUT (mags, short range)


– 6.5 Grendel (Alexander Arms / 52,000 / intro 2003; SAAMI 2011)
– 6mm ARC (Hornady / 52,000 psi / 2020)

After reviewing and discarding five other contenders, my list ended up where it started with the 6.5 Grendel from Alexander Arms and the 6mm ARC from Hornady. Both cartridge cases come from the same lineage that includes the 7.62 x 39, .220 Russian, and the 6mm PPC which is still a “wildcat” cartridge and still winning matches. The Grendel got its launch in 2002 with a case design very close to a necked-up 6 PPC and has achieved significant market acceptance. Key decisions regarding the details of its design including shoulder length, neck length, and throat length were made before the design of the high ballistic coefficient bullets became popular. A real disadvantage.

The 6mm ARC was launched in June 2020 straight into the pandemic. As one gun writer noted, it is “nothing more than an updated version of the …6 mm PPC.” That’s not exactly true, since it is an improved version designed specifically to do three things:

1. Take advantage of modern bullets and powders not available to the 6.5 Grendel.
2. Allow heavy for caliber bullets with a high BCs to be fired from the AR.
3. Extend the reach of the AR-15/M-4 platform to 1000 yards and beyond,

It took almost 13 years for the 6.5 Creedmoor to come into its own and achieve broad market acceptance. The 6.5 Grendel took slightly longer at 18 years. Notwithstanding the supply issues caused by panic buying and shortages across ammo and rifles, I believe the 6mm ARC will become a mainstream option for the AR-15 platform. It met the needs of the DOD agency for which it was developed, and that agency has already ordered rifles and ammo. The ARC’s 200, 500, and 1000 yard performance beats the 6.5 Grendel for long-range target shooters. At practical hunting distances, they really are about the same.

The Grendel comes out on top in terms of a much larger number of factory loads designed for hunting. The ARC has only one option – Hornady and only one hunting bullet, the 103 gr ELD-X. There are more high ballistic coefficient bullets available to the handloader in the 6.5 caliber (.264) than in 6mm (.243). The two cartridges share the same bolt face spec to handle the fatter PPC-style case and can use the same magazines which are compatible with the AR’s magazine well. The mags take 25 rounds for either 6.5 or 6mm. Unless you plan extreme long-range shooting, the difference really boils down to a lighter 6mm bullet at a higher velocity or a heavier 6.5 mm bullet with almost the same terminal energy despite the slower launch speed.


Both cartridges provide a significant performance improvement over the .223/5.56 as well as the two newer .22 caliber cartridges. For loaded ammo, the Grendel wins hands down. Grendel hunting ammo averages almost $2.00 / round or $0.50 more than any of the three Hornady offerings for the ARC. The .22 Nosler is even more expensive at $2.50 / round.

What tipped the scale for me was the ready availability – in stock now– of complete upper receivers as well complete rifles for the 6mm ARC. The Hornady 103 gr ELD-X ammo (extreme long distance expanding) was also in stock at several vendors. I opted for an Aero Precision complete upper receiver with a Ballistic Advantage 18” barrel plus 100 rounds of the 103 gr ELD-X and another 100 rounds of 108 gr ELD Match. I ordered magazines that had an excellent reputation for reliability with the 6.5 Grendel in 10-round and 25-round capacities. Since I could not find 6 ARC brass anywhere online, I reasoned that I would soon be creating my own once-fired brass and bought a set of reloading dies.

I have a red dot sight on my 16” .300 Blackout receiver and a 1-6X scope on my 5.56 receiver that works well for shorter ranges and out to 300 yards. For this new receiver, I opted for a Leupold 4-12X scope with parallax adjustment – very helpful for longer ranges. Since I anticipated the need for some quick shots on target like deer or antelope as well as carefully measured shots on coyotes and prairie dogs, I opted for a relatively simple reticle and decided to skip the benefits of a full mil dot option. All of this will be subject to revision after this fall’s deer trip.

There is very little time to get ready for a hunt this fall, but you have a whole year to pull together all the pieces you need if you decide to try either the 6.5 Grendel or the 6 ARC. In fact, depending on your circumstances and a little longer time to shop, you could decide on any of the cartridges discussed above and do very well.