I grew up around hunters.
Not tree-stand-sitting recreational hunters dressed up like the front cover of a Cabella’s catalog, but wilderness hunters in blue jeans and flannel shirts, whose families went without if their hunts were unsuccessful. They were more interested in placing shots and tracking animals than memorizing the ballistic data on the latest ubermagnum. Results mattered, not numbers. They hunted with .30-30s, .348 WCFs, .30-06s, .270s, and 6.5×55 Swedes and the like.
Growing up, I heard an oft-repeated statement from those who hunted with the Swedish 6.5 cartridge. “It just seems to kill better.” Better than an ‘aught-six, more effective than a .308. Better than a lot of things. They couldn’t tell me exactly why, but I learned to love the 6.5 mm cartridges for the same practical reasons, and I have since learned the science behind what those older hunters knew from experience.
Let’s put aside all we have learned from high-pressure marketing and gun-counter mythology, and focus on what we can learn from what counts: science and experience. That’s why I sold my .308 AR and replaced it with a 6.5 Grendel.
6.5 Grendel was my choice for hunting in New Zealand
Weight and Balance
The AR-15 weighs less than a similarly configured .308 AR. It is also shorter with the same barrel length. The balance is noticeably better. Because the 6.5 Grendel is designed for a standard-sized AR-15 rifle, the 6.5 Grendel has an advantage in weight and balance.
Price
A 6.5 Grendel rifle from Alexander Arms will tend to be less expensive than most .308 ARs of similar configuration and quality. Alexander Arms is very stringent with quality control on components and construction, so they produce very high quality guns. If you already have an AR-15 or AR-15 lower, a 6.5 Grendel upper drops on in seconds, so to have a Grendel rifle you need only purchase an upper and magazines.
6.5 Grendel offers an advantage in cost over a .308 AR.
Barrel Length
When all else is equal, a shorter barrel is more accurate than a longer barrel. The 6.5 Grendel, designed for the AR-15 and taking advantage of modern powders and cartridge design, is very efficient from a short barrel, gaining its velocity rapidly.
For hunting at longer ranges, a .308 requires a longer barrel to gain the required velocity for expansion. A load with a similar bullet type has a muzzle velocity of 2,387 in a 16.5″ .308, while the same type cartridge in a 16″ 6.5 Grendel has a 2,580 fps muzzle velocity with a much higher ballistic coefficient and sectional density than the .308. A .308 with a short barrel is also concussively loud.
The shorter barrel is more maneuverable, lighter, and balances nicely. I chose an 18″ barrel on my 6.5 Grendel, because I hunt in areas where very long-range shots are common. 18″, to me, is maximum practical length for a Grendel rifle intended for typical hunting. Most hunters would be well served with a 16″ or shorter barrel.
The Grendel has a strong advantage over .308 in practical barrel lengths.
Ammunition weight
6.5 Grendel ammunition weighs less and requires less space than .308 ammo. This may seem trivial, but can be a real advantage on long hunts, fly-in hunts in which weight is severely limited, or when meeting luggage weight or space requirements. I have been in fly-in trips in floatplanes in which we had to strip everything not absolutely essential from our gear, including some of our ammo, in order to stay under weight restrictions.
Recoil
Recoil is always a factor. Recoil fatigues the shooter and causes degradation of accuracy (varying in severity depending upon the experience of the shooter). Recoil slows re-acquisition of the target for a follow up shot.
The Grendel cartridge has substantially less recoil than a .308, even though the Grendel is a lighter rifle.
My daughter can readily manage the 6.5 Grendel
Terminal Ballistics
Sectional density greatly affects the terminal ballistics of a bullet (how it performs once it strikes its target).
A lighter, smaller diameter bullet can expand and penetrate better than a larger caliber bullet with poorer sectional density. This effectiveness is not a simple matter of bore size and bullet weight; it is a result of what shape the weight is formed into. For a .308 to have the same sectional density as a 6.5 mm, it would have to be longer and heavier than is possible chamber in a .308 chamber.
Imagine a guy standing on a diving board over a pool filled with orange Jello®. He bends his knees, raises his arms, and executes a perfect belly flop. As you wipe of a bit of Jello® that is crawling down your cheek, you notice his identical twin leave the same diving board and dive expertly into the Jello®. Both are now suspended in the quivering pool like bullets in ballistic gelatin. Which one penetrated deeper? The one who hit the Jello® vertically, of course. Both weighed exactly the same, but one had a much higher sectional density.
High sectional density helps bullets penetrate at longer ranges when velocity drops, and bullets with a combination of high sectional density and high ballistic coefficient retain their velocity over longer ranges.
Almost all 6.5mm bullets have excellent sectional density, so performance on game is outstanding, at least as good as, and usually better, than most .308 bullets.
From my New Zealand Goat Hunt
Ballistic Coefficient
To simplify, the ballistic coefficient effects how the bullet slices through the air. It affects velocity loss, trajectory, and the effect of wind on the bullet. High ballistic coefficients are desirable in most cases, especially for longer shots. 6.5mm bullets usually have higher BCs than .308 bullets
Velocity Retention
Closely related to the previous points, retention of velocity in important in hunting. Velocity is overrated by those who equate energy with killing potential, but velocity is vital to the killing performance of a bullet in an important way. Every bullet has a minimum velocity at which it will expand as intended. If a bullet is traveling below this threshold speed when it hits an animal, the bullet will not expand (or fragment) and may result in a wounded animal.
6.5 Grendel bullets usually retain their velocity much better than .308 bullets, extending the practical range that game may be taken. The Grendel projectile starts out much slower than .308 at the muzzle, yet is traveling substantially faster than .308 at 1000 meters. The result? The window in which Grendel bullets perform correctly is greater than the .308 window. This is because hunting bullets fail to perform well when their velocities are higher or lower than the velocity at which they were designed to perform (expand, fragment). A particular bullet design will perform well at both closer and farther ranges from a 6.5 Grendel than from a .308.
The Grendel bullets do this without requiring magnum-power loadings and blistering muzzle velocities, which means that recoil is very low and barrel life is vastly extended. This makes the 6.5 Grendel an excellent hunting cartridge at longer ranges.
The 6.5 Grendel also has a flatter trajectory, making holdovers and adjustments easier. Wind deflection is around half what many popular .308 bullets experience, so a slight misjudgment of wind will result in half the error with a 6.5 Grendel. A deflection of 8″ with the Grendel still puts the bullet in the kill zone, while a .308 in the same circumstances would impact 16″ from the point of aim, outside the kills zone of an animal.
Ammo Availability
This is an argument that people throw around a lot, but it does not make too much sense, when you think about it.
Do a few more stores carry .308 than carry 6.5 Grendel? Certainly. But I don’t need to buy ammo at every store. At most stores, I can’t buy the particular .308 hunting ammo that I would use anyway. I have never been out in some remote place trying to source ammo in a little village. If I’m traveling to hunt, I always take plenty of ammo with me.
I can buy 6.5 Grendel ammo in my local grocery store. I can buy it at a number of gun stores in my area. I traveled to New Zealand with a 6.5 Grendel rifle and found ammo in a New Zealand gun store as soon as I arrived. Wolf steel case 6.5 Grendel ammo is very high quality, as inexpensive as steel case 5.56 ammo, and, unlike the 5.56, the 6.5 Grendel chamber was designed to fire steel case ammunition. Anyone in the US can order the best 6.5 Grendel ammo directly from Alexander Arms and others.
So ammo availability is a non-issue for both calibers.
Common Sense
That’s why replacing a .308 AR with an Alexander Arms 6.5 Grendel makes obvious sense. 6.5 Grendel maintains velocity better at longer ranges with better penetration and expansion from a shorter, lighter rifle generating less recoil. Because it is flatter shooting with as much as half the wind deflection, errors in judging wind or range do not decrease accuracy as much.
Ammunition is easy to find and inexpensive, and the quality of Alexander Arms ammo and firearms is top of the line.
Having experienced first-hand the advantages of the 6.5 Grendel on my New Zealand Goat hunt and others, I will probably never buy another .308 AR.
I have an 18″ 6.5 Grendel that I built, and I love it. I have shot out to 400 yards with minimal holdover, and excellent grouping.
My next project build is a 20″, i have read that any more than that would be overkill.
What twist rate is needed on an 18” barrel. I have a 18” 1:8 twist and so far can not get bullets to group for anything. Going to try a little heavier ammo and see if that does the trick. But so far not loving my grendel like most.
I would want a twist rate of 1:7.5 on that barrel, ideally.
There are several factors that could be involved.
First variable is ammo, what have you tried?
Second is quality of the barrel.
I’m very careful about what barrels I would use for the Grendel. I usually stick with Alexander Arms because I know the quality I am getting with their barrels. There are some other manufacturers making quality barrels as well.
However, some years back, when Alexander Arms was using a different manufacturer for their barrels than they are now, I was approached by their barrel manufacturer, who offered me outstanding prices for the barrels that were rejected by AA as failing to pass their QC. The manufacturer was selling the failed barrels off through distributors and dealers since Alexander Arms would not use them.
This resulted in a lot of complaints about Grendel accuracy, but the fault was in the barrels.
Now the same manufacturer is building the same barrels for sale to distributors and other manufacturers, and many are going to be great barrels, but a percentage of them are not going to pass a stringent QC, as is always the case in manufacturing barrels, but they will still be sent off to whatever distributor of manufacturer that will take them.
So depending on where the barrel came from, quality could vary greatly, and often barrels from the same manufacturer will vary in quality between different distributors, depending on what they are willing to sell. This is also why some distributors sell the same brand of barrel much more expensive inexpensively than others distributors. It is because they are selling off reject barrels.
Also, some manufacturers have tried to come up with alternate chamber dimensions, which could affect accuracy.
All of this may or may not apply to your barrel.
However, what is suspect is that you may need to check accuracy at a longer range. The Grendel is one of those cartridges that tends to print wider groups at close range, and then accuracy tightens up.
Before anything else, if you have not yet, test accuracy at 100, 150, and 200 meters.
Oh, one other thing. Quality of the optic and mounts, and incorrect mounting methods are very often the cause of accuracy complaints. Even a top quality scope mounted incorrectly will often have adjustments drift under recoil initially.
So it may be an issue of elimination of possible factors.
Thank you. I am slowly going through and eliminating variables. I have shot the federal 120 grain soft points and I have tried the 123 grain Hornady sst. Going to try the 129 grain sst next. I have been sighting in at 100 as I fell that’s a good safe distance to zero a hunting rifle. I’ve put 60 rounds through it and not had much luck. Like I said I am going to try the 129 grain ammo and see if it groups. I have checked and remounted the scope. Did not think about the scope mounts themself. And will look st getting a new set of rings vs the cantilever mount I have on it now.
“The Grendel is one of those cartridges that tends to print wider groups at close range, and then accuracy tightens up”
Are you serious? Wider groups at close range and then it tightens up at longer range!!! Is that magic?
I’m sorry but I have to tell you that is Physically impossible unless your bullets have a self guidance mechanism….
Or maybe and just maybe it is possible because you are reloading with Pixie Dust rather than CFE 223. I would be able to argue with that.
Do a bit of research. As strange as it sounds, there are bullets that tend to shoot a slightly wider group at close range and then tighten up. A very simplistic explanation is that the bullet is doing a bit of a spiral and then the spin centers it on its path.
You can see this if you spin a child’s top. When first released, the top spins with a wobble, and the tip is describing a circle on the surface it is spinning on. If that surface is very smooth and clean and flat, the top will stabilize and the wobble will decrease until it spins with no noticeable wobble. While this takes place, the circle the tip is describing becomes smaller and smaller until the tip is spinning at the center of the first circles that the tip traveled in.
A bullet’s flight, especially a long high BC bullet spun fast, initially is not straight, but helical, with its trajectory at the center. As the bullet flies and velocity drops and drag works against the bullet, the helical motion diminishes and the bullet flies straight along its trajectory. But since the the initial helical path has at its center the actual trajectory of the bullet, each bullet is still following approximately the same trajectory. However, it they encounter a target at close range, they will be arrayed in different positions around that trajectory and group size will be bigger.
This is why a rifle can shoot 1 MOA at 50 meters and .5 MOA at 200 meters.
But 1 MOA at 50 is about .5″ and .5 MOA at 200 is about 1″ so often people do not notice.
However, there are cartridges that from some rifle could fire 3 MOA at 100m and .5 MOA at 500m.
Keep in mind that MOA is a measure of angle, and inches is a measure of distance; dont let that confuse you.
So while these bullets are traveling with a helical flight path, they are not sipping off at different angles, but flying a path that is centered on their trajectory, and stabilizing themselves to that trajectory.
You’re absolutely right. A bullet continues on a trajectory flight path that only diverges from the center of aim. Brian Litz, the ultimate guru of ballistics had offered a sizeable cash reward for anyone who can prove to him that it is possible for a larger group at close range to get tighter farther out. Nobody has taken him up on it, and nobody ever will because it’s impossible. A basic understanding of physics, including force vectors, etc clears the myth of the “settling” bullet up real quick.
Rounds can stabilize better later in their trajectory.
“wider groups at close range” isn’t an accurate way of wording it, but I know what he’s talking about.
For example I have a rifle that with some ammo will print 0.75″ groups at 25 yards, practically identical groups at 50 yards (maybe just a hair larger), then 1″ groups at 100 yards.
That’s not technically “larger” groups at closer range, but a 0.75″ group at 25 yds you’d expect to mean closer to 3″ groups at 100 yards…but that’s definitely not what happens.
So the groups themselves don’t tighten up (yes, that would be physically impossible) but the MOA measurement does tighten up quite a bit because of the bullet stabilizing a bit better later in the trajectory.
I would want a twist rate of 1:7.5 on that barrel, ideally.
There are several factors that could be involved.
First variable is ammo, what have you tried?
Second is quality of the barrel.
I’m very careful about what barrels I would use for the Grendel. I usually stick with Alexander Arms because I know the quality I am getting with their barrels. There are some other manufacturers making quality barrels as well.
However, some years back, when Alexander Arms was using a different manufacturer for their barrels than they are now, I was approached by their barrel manufacturer, who offered me outstanding prices for the barrels that were rejected by AA as failing to pass their QC. The manufacturer was selling the failed barrels off through distributors and dealers since Alexander Arms would not use them.
This resulted in a lot of complaints about Grendel accuracy, but the fault was in the barrels.
Now the same manufacturer is building the same barrels for sale to distributors and other manufacturers, and many are going to be great barrels, but a percentage of them are not going to pass a stringent QC, as is always the case in manufacturing barrels, but they will still be sent off to whatever distributor of manufacturer that will take them.
So depending on where the barrel came from, quality could vary greatly, and often barrels from the same manufacturer will vary in quality between different distributors, depending on what they are willing to sell. This is also why some distributors sell the same brand of barrel much more expensive inexpensively than others distributors. It is because they are selling off reject barrels.
Also, some manufacturers have tried to come up with alternate chamber dimensions, which could affect accuracy.
All of this may or may not apply to your barrel.
However, what is suspect is that you may need to check accuracy at a longer range. The Grendel is one of those cartridges that tends to print wider groups at close range, and then accuracy tightens up.
Before anything else, if you have not yet, test accuracy at 100, 150, and 200 meters.
Oh, one other thing. Quality of the optic and mounts, and incorrect mounting methods are very often the cause of accuracy complaints. Even a top quality scope mounted incorrectly will often have adjustments drift under recoil initially.
So it may be an issue of elimination of possible factors.
I have better “MOA” at 200 yards than at 100 yards with my 18 inch Grendel also and have seen others that have the same results. It isn’t impossible. I have heard of that for years. It is not a phenomena. It has to do with spin rate at a short distance. Also once the barrel is broken in, the 100 yard groups seem to tighten up i also notice a higher group when shooting 1000 yards and longer with a Creedmoorwhen shooting east to west than when shooting west to east. it;s called the coriolis effect. it is un noticeable under 1000 yards. So don’t just assume you have balistics all figured out according to common sense. It’s a science.
Depends on what you mean by overkill, there’s guys drilling 3×3 squares at 1000 yds with 24″ barrels.. but yeah I get what you mean 20″ is going to get you well past “can see easily without a scope”
`NICE ARTICLE I HAVE ONE OF YOUR EXAMPLES AND I HAVE TO ADMIT IT IS THE MOST ACCURATE CARTRIDGE I HAVE EVER SHOT, AND I AM 67 YEARS YOUNG AND HAVE FIRED A LOT OF ROUNDS
Love my Grendel !! I have had some issues with the `123 gr SST Hornady. I want to try 123 Gr Vmax for deer. I was not getting an exit wound with 123 Gr SST. I hope this solves the problem. I tried the 130 Swft Sorocco but my rifle does not group them as tight. It will nail drive the 123 Gr
Try the 120gr Barnes SST or the 120 gr Nosler BT loads from Alexander Arms.
The Barnes SST will most certainly exit, and reliably gives outstanding results. The Nosler Ballistic tip has a strong reputation for expanding reliably at lower velocities (longer ranges) but not so wildly as to prevent penetration.
I Love my 18 inch barrel Grendel. Last year I shot a buck at 223 yards. Bullet went thru and thru. buck ran 30 yard and expired. Recoil was like a 22 magnum with the 6.5 Grendel. love it. won’t hunt with anything else but the Grendel. Its lightweight, easy to carry and will kill anything I need to shoot>
What? Sell my .308 AR-10, not on your life. especially since I built it. But hell yes I’m going to build a 6.5 Grendel. Keep up the great articles.
No way am I selling my .308 AR, especially since I built it with some pretty nice components. But, hell yes I’m going to build a 6.5 Grendel. Keep up the great articles!
I personally feel that just because you like the 6.5 in know way justifies the getting rid of 308. While 6.5 is great for punching paper farther then the 308, it still doesn’t compare to the energy you get from 308. This would have been a better article to talk about where the 6.5 can fill a nitch. Not replace.
Energy sells cartridges. Energy is in no way a measure of killing power.
I’m interested in hearing from anyone who can scientifically prove me wrong on this.
It may not be a way to measure of killing but energy plays a big role if you dont have energy you dont have velocity. Thats why you see Ft-lb´s along with velocity and when the primer is struck the gun powder propels the bullet down the barrel thats called energy witch gives us velocity it definitely doesn’t sell bullets lol
This is James again. This December I killed 2 bucks with my 6.5 Grendel . One was at 100 yards and the other was at 80 yards. Both deer dropped in their tracks. I love my Grendel with the 18inch barrel. I’m 66 years old and don’t carry anything else. No more bolt-guns for me. Semi-auto 6.5 Grendel for flat shooting long range if need be, low recoil(like a 22mag). Trying to talk my brothers in getting a Grendel. My oldest brother saw one of the 6.5 bullets and he said “How will that little bullet kill a deer?” I’ve shot 3 so far with “That little bullet”.I love my Grendel.
I have an 18 in h Grendel as well as an 11.5 in pistol. Most of the time the pistol would do just fine but the 18 inch is nice.
Are you aware that you said that a shorter barrel equals better accuracy ??? If so. Where in the world did you get this ridiculous information ?
What I actually said is that “if all things are equal, a shorter barrel is more accurate.”
There is a common myth that longer barrels equal better accuracy. This is false, though there are two ways in which a longer barrel, though not more accurate in themselves, can cause a shooter to shoot more accurately.
The myth of longer barrels being more accurate originated from the days of black powder, but n which long range shooting required a very long, heavy bullet with a lot of powder to move it. Black powder burns slow. It does not actually detonate like smokeless powder does. So it needs a much longer bore in which to expand in order to fully accelerate the bullet. So long barrels were used to get the bullet going fast enough to stabilize and to reach the ranges they shot to in competition.
But even in those days, it was discovered that the two-band Enfield 1858 rifles with shorter, stiffer barrels than most military rifles of the day, proved more accurate and were the main rifle issued to Confederate sharpshooters in the Civil War.
Smokeless powder required much shorter barrels, and has become even more efficient in modern times, capable of building velocity much faster. Modern cartridge design takes advantage of that, and many modern cartridges gain their velocity in relatively short barrels. So velocity is no longer an issue.
Now for the mechanics of accuracy. If we isolate the barrel, we can look at how harmonics affect accuracy in a barrel. When the explosion happens in the chamber, the barrel begins to vibrate like a tuning fork. This vibration causes the tip of the barrel to describe an oval on the air. IF the tip of the barrel is in exactly the same place in its orbit every time a bullet leaves the bore, and if the vibration is exactly consistent from shot to shot, the barrel will be more accurate. However, there will always be some variation, more or less depending on the particular barrel and the particular load, and this is seen in a loss of accuracy.
So how do we decrease the movement caused by the vibration of the barrel? We make the barrel stiffer. We increase the ratio between the barrel diameter and the barrel length. This can be done by increasing the barrel diameter, of it can be done by decreasing the barrel length.
So in most cases, if you take a 24” barrel and cut it down to 20” or 18”, you will see a measurable increase in accuracy. A shorter barrel is a stiffer barrel, and therefore a more accurate barrel.
This is well documented. GPS Sniper School, for example, have cut many police department .308 sniper rifles down to 18” from .24” and have documented substantial accuracy gains. Same rifle, same barrel, becomes more accurate when 6” are cut off the barrel.
Now there may be other trade offs, but the fact remains that if all else is equal, a shorter barrel is more accurate.
Now, I previously mentioned the shooter’s accuracy. If the shooter is using iron sights, a longer sight radius will tend to make the shooter himself little more accurate. If a shooter is firing offhand, more weight out front can steady the rifle. So there are circumstances in which a longer barrel can help a shooter shoot a bit more accurately, but the gun itself is not more accurate.
Wow. Nicely phrased and well thought out.
Short barrels are stiffer thus they shoot more accurately. We are not talking iron sights and the distance between them. We are using a good scope. Do a bit of research. You will learn plenty about it.
Great article, I found this incredibly helpful. I have wondered if the Grendel round would be sufficient for elk. And since a 308 is plenty for elk then I have no worries with the Grendel.
Yeah well, 308Win has quite a performance and purpose range. There’s a lot of hunting style / military style low powered and low BC ammo around, which you’ll probably not find for the 6.5.
Use comparable, modern ammo in the upper performance spectrum for both, and the 308 will still GREATLY outperform the Grendel in every single ballistic aspect. (Just look at the 168gr ELD / 178gr BTHP factory loads from Hornady. Some of those reach 3000ftlbs with faster, heavier, better BC bullets than a 123gr SST.)
That it will do so at the cost of more recoil and concussion and out of a more bulky platform remains true, of course.
We are talking about hunting here, so I compared equivalent hunting loads/bullets. The bullets you mentioned are not suited for hunting, although I am excited to see that Hornady in bringing better high-bc hunting bullets to the market now in many calibers.
I am not concerned with foot-pounds of energy. No one has ever been able to prove to me that energy has any reliable effect on the killing of game, except as it affects bullet expansion and penetration.
Let’s do the same bullet type with Litz G7 values then…
24″ barrels:
-123gr SST (.236G7, .252SD), 28.9gr of AA2520 –> 2644fps
-180gr SST (.253G7, .271SD), 43.0gr of AA2520 –> 2647fps
These loads are both 52kPSI which is basically a 16% underpressure handycap for the .308Win (62kPSI SAAMI), resulting in a loss of ~120fps.
Still the Grendel loses:
less sectional density, lower BC, slower, lighter, smaller:
6% more drop , 11% more drift, 40% less energy @ 1000 yards.
Also, where’s the so claimed short barrel advantage of the 6.5Grendel over the 308Win? In 16″ guns the resulting velocities arr 2435 and 2439fps respectively… So other than the wish to not go deaf from the .308Win, I don’t see why short barrels should in any way favor the 6.5…
Yeah, energy is nonsense, that’s why .380ACP is identical to .357Mag, and stuff like .375H&H has no reason to exist in the first place.
People should be shooting .204Ruger exclusively. Lel.
Even if you don’t believe in energy, frontal area, velocity, sectional density on top of better ballistics should convince you?
built me a Grendel tack driver using a 20 BSF barrel. I used high end parts through out and enjoy the looks I get when people see all that carbon fiber. The Scope and mount did add a lot of weight though. 3.5-25×56 scope that uses a 35mm tube adds weight even at 13.8” long. Stunning gun though.
Weight and Balance: True, potentially lighter 6.5G build.
Price: You make this out to be a caliber-debate. A 6.5G gun is not usually inherently cheaper.
Barrel Length: 308Win does rather okay in short barrels. 23xx fps from a 308Win seems awfully low. Why don’t you provide some more insight on the type of load used.
Ammunition weight: True. 6.5G weighs less.
Recoil: True. Push a bigger bullet downrange at greater speed and you’ll feel it.
Terminal Ballistics: Penetration is not usually an issue with either one of those calibers. If in doubt, feel free to use any of the higher sectional densitly 308 projectiles. 168gr .30cal will match the 123gr 6.5G’s SD. Apart from that: You can have a bigger, heavier bullet at higher velocities with the 308. No way to justify giving this point to the 6.5
Ballistic Coefficient / Velocity Retention: Absolutely no. Plenty of 308Win load choices that have better ballistic coefficients and velocities than any Grendel load. Less drop, drift and more energy at all ranges with the 308.
Ammo Availability: The 6.5G may be similarly prevalent. Not any better though. Remember: The 28ct-Surplus 6.5 is not one of the ballistically amazing loads that everybody is preaching when talking about the Grendel.
Common Sense: Common sense says, I’ll get the caliber that best does what I want it to do. Purely based on ballistics, the 6.5G is worse in every aspect. If you want an jack-of-all trades AR build, the 6.5 may be the superior choice.
I agree… You shouldn’t compare the ballistics of a 125g 308 to a 125g 6.5 Grendel. The article never actually states the bullet weight of the 308 but he does say similarly sized, so it seems like this is what is being done. I agree if you use a heavier 308 in this comparison, things change up a bit. I also agree the 308 isn’t the best caliber ever, but neither is the 6.5 Grendel. Have one of each, and use the right tool for the right job. And it’s OK to have a favorite, but that doesn’t make it the best, hands down.
I have studied the Grendel for some time and I’ll probably build one sooner than an AR10, because it is cheaper (only need an upper since I have other AR15s) and would be good for Texas sized deer, hogs, and coyotes. But I still want a 308 AR10 to go along with my 308 bolt gun. It’s all part of having a balanced diet!
I never gave numbers for any 125gr .308. I wouldn’t consider ever loading a bullet that light in a .308. I never even said similar sized, as a .308 bullet can’t be similarly sized to a .264.
All in All, I will be 58 years old this Sept. I have owned and fired many guns in my life. I have shot many deer with my life long .270 Win. bolt , my go to gun. But after having an AR built in 6.5 Grendel and harvesting a few whitetail with it, I will now call this my go to gun, I love the accuracy and performance from 55 yard shot to 440 yard shot on whitetail. Central Wis.
It’s so funny when people start comparing apples to oranges and try to make a case for it and how one is better than the other, I own an Sig Sauer AR 716 in 308 and built my 6.5 Grendel with Spikes Tactical lower and BCM upper 18″ barrel, both of them print 1MOA or less at 100 yrds, they are two very different weapons that have their use and purpose, I reload so I can maximize hone in to the advantages of each.
For hunting medium and large game the 308 works great with 178 grain Hornady ELDX and 41.9 grains of Acc 2460 flying at 2480 fps, the 6.5 Grendel likes 129 grain Hornady Interbond, with 32.1 grains of CFE223 flying at 2330 fps,they are both devastating rounds on game and they have their place but I wouldn’t use them for the same situations, if you like numbers consider the following, the above mentioned 308 has a G1 BC of .552 and a SD of .268 and the 6.5 has a G1 BC of .480 and a SD of .264 so if you compare the two the 308 has better ballistic coefficient and about the same penetration on game all that with about 150 fps more than the 6.5 and also a heavier and larger bullet so in that particular case the 308 wins hands down unless the added 4Lbs on the gun is hard for you to deal with.
The majority of people use the 147 &150 grain in their 308 because that is what is common but that was developed as a FMJ military based round to wound the enemy and not to hunt with although some can make an argument for it but the wounding effects are vastly different.
I would use the heavier bullets all day long for most applications other than short range target practice and very small game at shorter distances. .308 caliber bullets without a doubt have the largest selection and can range from somewhere around 110 up to about 230 grains from most bullet manufacturers and a ton of military surplus, shall we say, with beautiful color codes on them ranging from the common FMJ to tracers, penetrators and even HE so definitely you’ll be able to find your flavor among those.
The 6.5 Grendel has less variety of bullets but nonetheless it shines with bullets ranging from about 95 grains for varmint to 130 grains for deer and even elk but due to the higher weight of the bullet and lower powder case capacity the more the weight the lower the velocity so closer distances may be optimal to conserve the necessary energy to penetrate thick bone and muscle.
In essence both calibers are great and have a spot where they shine, just know were to use them, remember that time and place is important as well…. don’t be that guy that wears dress shoes at the beach and sandals to a suit and tie dinner.
I agree. The .308 was developed to replicate the .30-06 military loads with the smaller case size made possible with advances in powders.
The velocity-over-everything-else guys love the lighter .308 bullets because they get high initial velocity, but they don’t really understand exterior or terminal ballistics, or they would trade that velocity for longer, heavier bullets. A light bullet that shoots fast initially drops off quickly after a point.
Ideally, a good .30 cal bullet would be well over 200 grains for best long-range performance, but unfortunately, we can’t stuff a high-BC 220 grain bullet into a .308 magazine or chamber, or put enough powder behind it in a .308 case.
The same is true for a Grendel. It approximates the effectiveness of a .308 because like the .308, it can’t push the best lenght-for-diameter bullets for it’s caliber and still fullfill the intended role (feed from 5.56-size mags through an AR-15). Now, when we start talking about handloading in a bolt-action, the Grendel can do even more spectacular things, but the purpose for this article is a discussion or AR rifles. In a bolt action, a 6.5-284 Norma, 6.5-06, 6.5 Creedmore, or 6.6×55 can tromp the .308 because they can fire higher BC bullets at higher velocities.
I’m thrilled with companies like Hornady bringing out hunting bullets that match the BCs of match bullets – it is a game changer for sure. It used to be that you could shoot great high BC match bullets from your .308, and then your hunting loads fired a completely dissimilar trajectory.
However, for hunting, my Grendel will do everything for me that a .308 will do in an AR, except for one thing, so I will chose it over a .308 AR for hunting purposes.
A .308 in a bolt gun can shoot heavy round-nose bullets for close range against bears, so it certainly has an edge for that specific purpose.
A lot of the comments are focused on the best match bullets for the .308, or bolt-gun performance.
The purpose of the article is to compare hunting performance out of semi-auto AR rifles or AR-pistols.
For these purposes, anything I can do with a .308 AR I can accomplish just as well or sometimes better with a 6.5 Grendel AR.
So what bullets would you consider using in a hunting scenario?
Also, it’s not like the 6.5G won’t suffer from shorter barrels. Just as a quick comparison:
130gr (SD 0.187g/mm², G1 .488) vs 180gr (SD 0.191g/mm², G1 .507) Accubonds will max out somewhere around…
2371 fps (16″) to 2580 fps (24″) in the Grendel
2460 fps (16″) to 2680 fps (24″) in the .308Win
Approximately 8% loss in both cases, so I don’t see how the Grendel wins in the barrel length department, especially since the .308Win is still faster.
Heck, you could start questioning the weight and balances of the platform too since the 308 can be cut down shorter and still deliver the same velocities with the 180gr bullet…
I can push a 130 grain Barnes TTSX at 3,200 FPS from my 20 inch 308 AR-10. I hunt hogs here in Texas and rarely shoot more than 150 yards while doing so. I assure you the damage produced by that 308 round is much more devastating than anything I can produce with my Grendel. I have shot steel at 500 yards with that load and it hits plates with much more authority than my Grendel as well. I would not want to shoot a decent size hog further than 400 to 500 yards with either round. They both have their place and an AR-15 is much lighter but I still prefer the extra energy from the 308 at reasonable ranges for larger tougher animals.
I’m not knocking .308, if anyone thinks I am, they didn’t read or understand the article.
However, again when we study ballistics, we have to compare things that are equal, understand our purposes, etc.
130 gr bullets are very light for .308. Since it is a TSX you are using, and they are long for their length, that increases performance somewhat. But if you want to compare a 130 gr .30” bullet to a 6.5mm bullet, you can’t compare it to a 120 or 130 gr bullet. You have to compare it to a much lighter 6.5 bullet.
Using a very light for caliber bullet may increase velocity, but performance suffers in almost every other way.
Increasing energy at close range doesn’t make any difference to me, because again, no one has yet to show me any reliable evidence that energy is a measure of killing potential.
What 6.5 Grendel does for me is allow me to use a shorter, lighter, quieter rifle with less recoil and have pretty much the same killing potential as I would with a .308.
If I was going to be using a .308-sized rifle, then I would, of course, be talking about 6.5×55, Creedmoor, or .260 rem. In a long-action rifle, it would be 6.5-284 Norma or 6.5’06, all of which increase performance well above .308 or .30-06 in most areas.
But Grendel gives me .308 or sometimes a little better killing potential in an AR15, Howa mini-action, or CZ mini-Mauser. That’s hard to beat.
Great article Dylan! I built a 6.5 Grendel about two years ago and love it. I built it a little too heavy but I shoot it off sticks, tripod or bipod most of the time. That is an amazing little caliber that many folks will not even take the time to read and give it a chance but we know the difference huh. I would not trade mine for the world and don’t pay too much attention to these over critical trolls.
Oh I get it now!
People that are equipped with ballistic data, knowledge and facts are the so called trolls now, nicely put my friend.
Thank you for teaching us that when you cannot win the argument you can always resort to the name calling to fill better about yourself.
I love the Grendel, but this article is a bit far out there for me… 6.5 Grendel is more than adequate and a pleasure to shoot, however it does not compare to my LR-308 slinging 178gr ELD-X’s with their .278 (G7) BC @ 2640 fps. The .308 shoots flatter, hits harder, and bucks the wind better.. The 6.5 Grendel is much lighter, more efficient with a bit longer barrel life. No need to disrespect one cartridge over another, keep them both and enjoy them for their respective strengths.
Ahh, NOW we are discussing reasonable bullets. The ELD-X bullets in the heavier weights are game changers for hunting at longer ranges.
Now .308 is designed to shoot lighter bullets than ideal for a .30” bore. The Grendel also is designed to shoot lighter bullets than ideal in a .264” bore.
This is because both are slightly limited by the purpose and the guns they are designed for. Neither are really limited in most of their range of potential use. However, when we start to asking about using 130gr of 150gr bullets in a .308, or 95gr or 100gr bullets in a 6.5, we are handicapping both cartridges.
175 gr in a .308 gets us into comparable bullets to the 120gr range in the 6.5.
With the ELD-X at 175gr in the .308, we get performance that almost no other hunting bullet gives us.
Since there isn’t a ELD-X at 120 gr in the 6.5 (there is a heavier one for larger 6.5 cartridges), we can’t quite compare apples with apples, but close.
If we take another Hornady bullet, the 123 gr SST, we start out at 40 fps slower that your 2640 fps ELD-X. Slightly lower BC. Slightly lower SD.
Now with mist .308 hunting bullets, 6.5 Grendel overtakes them in downrange performance. With the ELD-X, the .308 holds a slight edge.
At 1000m, .308 ELD-X is 21 fps faster, 4.6 moa less drop, 1 moa less wind drift at 10 mph.
For me, this isn’t enough of a difference to make me want to carry a .308 AR hunting, over an AR15. I’d be interested to see what a 123 gr ELD-X would look like in 6.5, but it may never happen, since it make more sense in the 140 gr range.
By the way, we disrespecting any cartridge.