3 Alternative AR-15 Rifle Chamberings To Consider

6.8 SPC vs 300 BLK ammunition military suppressed

Nick Leghorn for TTAG

Let’s face it: getting an AR rifle in .223/5.56 is BORING. It’s too easy! Everyone has one. It shows a lack of imagination.

Oh, okay, fine. .223 and 5.56 NATO has their virtues. It’s cheap, which means you can do a lot more shooting than with other chamberings. It’s proven in self-defense capacities, too. If you want to shoot a rifle in something other than .22 LR, but aren’t going to be doing a lot of hunting, it’s a good choice.

But what if you aspire to something besides the same ‘ol, same ‘ol?

Here are three AR rifle chamberings to look at if you want to do more than just punch paper. I’m leaving some details out for brevity; I could devote an entire article to each one of these cartridges on their own. If there’s something you think I missed, put it in the comments.

300 Blackout

.300 blk, 5.56 nato and 7.62x39

Three .300 BLK cartridges, one each of 5.56mm NATO and 7.62x39mm. (Courtesy Silencertalk [CC BY 3.0], via Wikimedia Commons)

The .300 BLK round — also known as .300 AAC Blackout or .300 Blackout — is another good choice in an intermediate caliber. The round was made by necking a .223 Remington up to accept a .308-caliber bullet. It’s basically just like the .300 Whisper, except it’s commercially successful. This gives the round certain advantages…but certain disadvantages too.

The .300 BLK was created to serve several needs. First, it had to fit the standard AR-15 action, so carrying capacity isn’t limited as it is with the AR-10. Second, it had to use a .30 caliber bullet to give it a bit more wallop, similar to 7.62x39mm.

Finally, it had to function without issues when the rifle is suppressed and/or when subsonic ammunition is used, as the M4 system functions best above a certain pressure threshold.

the perfect .300 BLK rifle

Nick Leghorn for TTAG

Obviously, that gives the round certain advantages for a special forces operator (makes a good close-quarters long gun) and for the recoil-conscious modern shooter who uses a suppressor. For handloaders, the round uses .308 projectiles, which basically means the world is your oyster so long as you stay within approved pressure levels.

Available bullet weights range from light varmint loads around 78 grains up to 220 grains. Velocities, depending on the load, can be anywhere from 1,000 to 3,000 fps from the muzzle, and energy can be 500 ft-lbs to just under 1,400 ft-lbs.

It’s great for plinking. It’s great for self-defense, and you can hunt with it, but it’s limited to shorter ranges. It makes an excellent cartridge for hogs or Eastern whitetails (we grow ’em bigger on the Left Coast) in heavily-wooded areas.

In other words, it’s a tactical .30-30. Nothing wrong with that!

.458 SOCOM

If you want even more of a wallop, there’s the .458 SOCOM.

Credit: US Gov’t/Wikimedia Commons

The .458 SOCOM – in addition to the .450 Bushmaster, which is the .45 Professional wildcat with a haircut – was designed to put a big bore bullet in a small case that will fit in a standard AR-15 frame.

The legend goes that some military personnel found that Somali fighters (during the Mogadishu campaign) weren’t as effectively deterred by 5.56 because they chewed khat. Khat is a plant, the leaves of which contain cathinone, an alkaloid with similar properties to cocaine. So, the cartridge was designed by Marty ter Weeme of Teppo Jutsu.

If your day is done, and you want to ride on, cathinone…eh. Doesn’t work. Anyway . . .

The difference between the two is that .458 SOCOM is a necked-up .50 AE case, with a .458-in projectile. By contrast, .450 BM is a necked-up .284 Winchester with a .452-inch projectile, the same as .45 ACP, .45 Colt and .45-70 Gov’t.

Both operate at less than 40,000 psi of chamber pressure, both are used with similar bullet weights (250 grains and up) and both achieve similar velocities and muzzle energies.

Velocity and energy ranges by bullet weight and load, ranging from around 2,100 fps and 2500 ft-lbs with a 250-gr. projectile to around 1,000 fps and 1300 ft-lbs with a 600-gr. projectile. If you love the AR platform, but want to put a BIG HOLE in something…this is the ticket. There are some caveats, though.

First, it’s expensive. Second, capacity is drastically reduced compared to .223, in that magazines need to be single-stack due to the size of the round. A 20-round magazine for .223 holds 7 rounds of .458, a 30-rounder holds 10. Third, forget long-range.

Just like .300 BLK, though, .458 makes a great self-defense gun. It also makes a great hunting round for short-range; with a suitable bullet, it could take any game in North America. Unfortunately, it appears that .458 SOCOM hasn’t been approved for straight-wall jurisdictions…though .450 Bushmaster is.

Basically, you could think of .458 SOCOM as a high-tech .45-70.

6.8 SPC

Lastly, we come to 6.8 SPC. The 6.8mm Remington Special Purpose Cartridge was developed for Armed Forces testing.

They had the idea that the 5.56mm was lacking at longer ranges, and also that the 6mm family had a lot of potential for use as a sniper cartridge given its great accuracy and lower recoil than .30-caliber rounds such as 7.62x51mm and .300 Winchester Magnum.

6.8mm SPC on the left, .223 Remington on the right. Credit: Hellbus [CC BY-SA 4.0], via Wikimedia Commons

The US Army Marksmanship Unit did some toying around, eventually arriving at a 6.8mm bullet as having the best attributes, and got Remington to cook up the ammo. The idea stuck, as the Armed Forces are purportedly going to switch to a 6.5mm or 6.8mm cartridge as their standard round sometime in the near future.

This is, of course, a modern take on a very old idea.

Remington and Winchester cooked up cartridges with the same design ethos (put smaller bullet in case, bullet go faster and farther) which led to the 7mm Remington Magnum and the .270 Winchester, among many others (like the .25-06, .280 Remington, .257 Roberts, ad inifinitum) one could name. Gun writers like Warren Page and Jack O’Connor certainly helped sell them.

Obviously, it had to be adapted to the AR-15 platform, so Remington trimmed the obscure .30 Remington (basically a .30-30 for non-lever-action rifles) down and inserted a 6.8mm bullet (.270 caliber in case you’re curious; like I said, it’s just a tactical variation on an established theme) in the case. Overall length is 2.26 inches, the same as .223 Remington/5.56mm.

However, it isn’t a tactical .270, and the reason why is the shorter case. You see, .270 Winchester has a case length of 2.54 inches vs 1.667 inches for the 6.8 SPC, so the heavier bullets (120 grains and up) are too long to seat in the case. Thus, cartridges are limited to about 115 grains in most factory loadings.

That said, the 6.8 SPC entered field testing with the armed forces, and with very positive results. While it has less muzzle velocity than 5.56, it makes up for it with a higher ballistic coefficient, so a 110-grain 6.8mm SPC bullet has the same velocity at 400 yards as a 55-grain 5.56 M193 round does at the same distance despite leaving the muzzle at 400 fewer feet per second and also carrying 400 more ft-lbs of energy.

It was also found to still be effective at close and moderately longer distances (say out to 600 yards) from carbine and SBR barrel lengths, and quite controllable in full-auto. In short, a jack of all trades that’s quite decent.

In the civilian realm, it’s found adoption with folks who hunt with an AR-platform rifle but not at uber-long ranges.

If you wanted an intermediate cartridge that had more punch than .223, and longer legs, but didn’t want to go whole-hog on an AR-10…this would be the ticket. Basically it’s a tactical .270, though without the same breadth of capability of one. Then again, most people who buy one aren’t going to be hunting, so who cares?

What about you? Is there a different alternative AR rifle cartridge that you’re more interested in? Tell us about it in the comments.

comments

  1. avatar Green Mtn. Boy says:

    I take my AR’s chambered in 30-30 semi auto aka 300 AAC Blackout.

    1. avatar Art out West says:

      I haven’t bought one yet, but the 6.5 Grendel looks interesting. They .300 Blackout seems like a great option for pistol ARs. For a rifle, maybe. I’ve already got an AK.

      1. avatar Buffer says:

        Change rounds because the 5.56 is boring and everyone has one? That’s the dumbest advice I’ve ever heard.

        The mission drives the decision. This article reads like an insecure teenager wrote it trying to sound cool but instead just confirmed that he’s nothing but a little nervous mall ninja.

        1. avatar Dude says:

          I read it as the author injecting some humor into the article.

        2. avatar merlin grayman says:

          jeez … grow a sense of humor.

        3. avatar Buffer says:

          Me or the author….or you?

        4. avatar G. says:

          Buffer, we get enough flake about our guns from the gun grabbers without disparaging our own. Oh, maybe you are a gun grabber.

        5. avatar clint chapman says:

          Take it easy Francis…

      2. avatar Ransom says:

        Yeah, I threw together a PSA .300blk pistol. Great shooter. The cartridge retains more of its intended velocity from a shorty than 5.56. Still a little pricey though. I stock up when I see em in the $0.40 range.

      3. avatar Jeremy B. says:

        6.5 Grendel is fine (I guess) but it’s performance suffers greatly with shorter barrels.

        And if you aren’t shooting past 400 yards then the 6.8 is probably a better option.

        If you are shooting past 400 yards, the 22 Valkyrie is probably a better option.

        1. avatar Ben S. says:

          Performance does not suffer “greatly” from shorter barrels. It was designed to fire from an 18-20″ barrel. Shortening to 16″ you lose maybe a hundred to a hundred and fifty fps. Maybe. As short as 14.5″ will still give you 500 ft-lbs of energy at 750 yards per Alexander Arms data sheets, and most nighttime pig hunters who use the caliber are using 12.5″ barrels with suppressors and dropping hogs very well out to 200 yards in the dead of night with it. It’s fine in shorter barrels, it’s just not quite as forgiving as the 6.8, which has a closer case capacity to bore diameter ratio.

        2. avatar mrbadnews says:

          My 16″ 6.5 Grendel does 2500 average with Hornady 123s form a Blackhole Weaponry tube… That ain’t bad,.. and Taylor KO numbers are nearly twice the Valkyre in the same length barrel. So,.. what the heck are you comparing?

      4. avatar Ed Schrade says:

        Get the 6.5 Grendel, you will not be sorry ! 20 in. barrel.

        1. avatar No One Special says:

          Good advice or even better get both as funds allow.

        2. avatar Mantitude says:

          I have a Larue 6.5 Grendel that I love dearly.
          It has an 18″ barrel, but a midlength gas system, which is my only real gripe.
          I intend to stick a Faxon or Lothar-Walther 20″ with a rifle-length gas system in it’s place eventually.
          But for now, it’s working well enough for me to not be too worried about switching it. I mean, heck, it’s shooting to about 1.5moa at 100yards with Wolf steel, of all things!

        3. avatar No One Special says:

          I have the a Faxon 20″ heavy fluted 6.5 Grendel barrel and like it a lot. If you go with the Faxon get a BCG at the same time and pay the $10 extra for the headspaced and matched bolt.

    2. avatar Nate says:

      I have 300 blk with my Tavor x95 and it is very awesome.

  2. avatar B.D. says:

    .458 lol. C’mon man… It’s a pretty awesome round. But worth considering for your AR? No. It’s penetration is not impressive either, but it’s ability to explode a watermelon makes for good YouTube hits.

    6.8 and .300 – ftw (for the win). Good choices. The .458 is something you see on “Demolition Ranch”, just for fun.

    If you don’t have a .300 BLK AR yet, what are you waiting for 😉

    1. avatar Evan says:

      Since I don’t own a suppressor, I don’t see the point in getting a .300BLK AR.

      Plus I have two in 5.56, and I’ve seen enough pictures of people who have accidentally put a mag loaded with .300BLK into their 5.56 AR with bad results.

      1. avatar Viejo Torro says:

        This on both accounts

      2. avatar D Y says:

        Makes a pistol AR legal for loaded carry in a vehicle in states that dont allow loaded rifles in vehicles, is above the threshold for projectile diameter in states with that restriction for hunting, and with the 110gr loadings, and again with an 8.5″ barrel has same muzzle energy as some .44 mag 300gr loads, yet with 30rds on tap.

        Yes, those are fairly niche parameters, but a fair number of them. Compared to other common rounds like x39 and 5.56, by fps/inch (not an average) 300 gains an exceptional amount by 9″, dropping off rapidly past that. Far better rounds when you start talking 10″+ barrels and supersonic loads however.

        Dont forget that you dont need many special components for the 300BO vs 5.56 either…Barrel. For those of us with no need for 5.56, cartridge interchange danger is minimal.

      3. avatar B.D. says:

        It’s all about those “pistols” man.

    2. avatar 300blknutswinger says:

      “If you don’t have a .300 BLK AR yet, what are you waiting for 😉”

      For it to be less than 50 cents a trigger pull for a 223 case necked out to accept a 30 cal projectile. Should be more comparable price wise to 7.62×39 and 223. For 50 cents a round its 308 all day, but if you want to waste you money on a neutered 308 for the same price per trigger pull, be my guest. The ammo manufactures love you!

  3. avatar Evan says:

    If you’re going to get a 6.8mm, go with the LWRC SIX8 and its proprietary lower and magazines.

    I understand that 6.8mm has problems in standard AR mags. And LWRC just makes an excellent all around rifle (I don’t have the SIX8, but I do have a 5.56mm M6IC).

    1. avatar Jeremy B. says:

      PRI makes excellent 6.8 mags for the standard AR platform. But the LWRC is super nice.

  4. avatar Gadsden Flag says:

    Other AR chamberings to consider? I wonder why anyone is considering an AR.

    1. avatar Thixotropic says:

      About 150 reasons.

      And I’ll take mine in 5.56×45. Plenty of good bullets and loadings to kill just about anything from Ghetto Baboons to Hogs. Yeah, Hogs.

      Idiot.

      1. avatar Gadsden Flag says:

        Thix, my problem is not with the calibers. It’s the AR platform. I was paid to use that piece of shit from 1979 until 2014. And owned at least three privately. Two Colts. After reading Peter Kokalis’ article “Bushmaster Builds a Better AR-15” I bought one. It wasn’t any more reliable than any other one I’d used. I understand why it’s so popular. It’s the only thing available at a reasonable price. Fortunately, I bought some real rifles when they were available at a reasonable price. After $50 factory rebate I had $350 in my first H&K 91. New in the box. Bought it when I was home on leave. Those were the days.

        1. avatar Gadsden Flag says:

          Thix, I’ve been waiting all afternoon for those 150 reasons to have an AR. Yet, the crickets chirp. I have to conclude that you’re a little confused about what’s your elbow, and what’s your asshole.

      2. avatar B.D. says:

        Yeah he says some wild shit every now and then, but questioning why people buy AR’s? Wow… just wow.

        1. avatar Gadsden Flag says:

          B.D., I know why people buy ARs. 1. They’re available. 2. They’re affordable. 3. For many, perhaps for most, it’s the only rifle of this type they’re familiar with. Get your hands on an H&K 93/33 then tell me what you think.

    2. avatar Gov. William J Le Petomane says:

      The problem with ARs is that the recoil spring (buffer) is in the wrong place. Even more annoying when you’re wearing muffs. That and I never understood what was wrong with the charging handle being attached to the bolt like every other semi-auto. The AR’s charging handle and forward assist are kind of stupid, IMHO.

      1. avatar Gadsden Flag says:

        Gov, that’s just the beginning of what’s wrong with the AR platform and not even the most serious. First is the direct gas impengment system. Nothing you can do about that. It is what it is. Even Eugene tried to correct it with the AR 18/180 and Stoner weapons system. Next, the magazine. Granted, P Mags, etc. are an improvement, but there are other issues. Magazines should lock up in the receiver at the top of the magazine. Fore and aft. See AK, HK, M-14, BM-59, FN FAL, shit, even a Mini 14. This stabilizes the magazine/feed lips for more reliable feeding. An AR magazine locks in with a single point on the left side of the magazine 2-3″ below the top of the magazine. The whole system is a mediocre design. Just because everyone uses it doesn’t change that.

  5. avatar Arc says:

    If you don’t want 5.56 or 300BLK just get an AR10 in whatever up powered cartridge you want. 300WM, 338Lapua, etc. The 500BECK vanished and went MIA though, so sad.

  6. avatar No One Special says:

    You forgot 6.5 Grendel. Which is a better round than the 6.8 SPC. Unless running a suppressor is an option 7.62X39 would be a better option than 300 blackout as well.

    1. avatar Johnny Go Lightly says:

      Second the Grendel. Double at least the bullet weight. Signnificant energy increase. Brings effective range out to 800 or 1000 yds.

      1. avatar Dude says:

        I was hoping to see 6.5 Grendel make the list. I’m very interested in this cartridge. The downside seems to be availability, and requiring more than a barrel swap. To me, it seems like a bigger change from 5.56 than the 6.8 SPC.

        1. avatar No One Special says:

          Not really especially if you are going to build it yourself from the ground up. When you buy the BCG just buy one for Grendel.

    2. avatar Rad Man says:

      Grendel is the only AR round I shoot. I think it’s the most capable and versatile round you can fire from an AR15.

      1. avatar pwrserge says:

        The problem with Grendel is the large case head. The AR-15 bolt was designed with the 5.56 case head size in mind and thus the bolt face was shrunk down to get the minimal bolt face you need for a reliable lockup and a minimal chance of shearing off locking lugs. Then the geniuses who designed Grendel decided to mill out a gigantic chunk of the bolt face leaving a far smaller contact surface with the barrel and a far inferior support for the locking lugs. To use something with a .30 cal sized case head, you need an AR10 bolt, not an AR15 bolt. The problem is that that almost 100% requires using an AR10 upper which comes down to “Why not just shoot a full power rifle cartridge in the first place?”

        1. avatar Rad Man says:

          Sorry, my reply was inserted below.

        2. avatar No One Special says:

          I have a 20″ Faxon heavy fluted barrel with matched BCG and haven’t had a problem one with mine. When Grendel first came out the bolt had issues but I haven’t heard anyone say anything like that in a while.

        3. avatar Erik Weisz says:

          There are Grendel II bolts now. They must be matched with Grendel II barrel extensions. This combo solves the issues you describe.

        4. avatar No One Special says:

          The barrel extension is the same. The difference is the depth of the bolt face between type 1 and 2 bolts. Type 1 has a bolt face depth of 0.125 which is the same as the 7.62X39 bolt face. Type 2 has a bolt face depth of 0.136. There is also a type 1 and 2 chamber and without going into a lot of detail the big difference in the chambers are in the throat and lead. A type 2 bolt and chamber are the way to go for reliability and durability.

      2. avatar No One Special says:

        I load and shoot Grendel and really like the round. I’ve helped a friend load and I have shot the 6.8 SPC and in my opinion there’s no comparison. I have 2 5.56 AR’s as well as a AR-308 chambered in 6.5 Creedmoor. The only other two I’m interested in is the 458 SOCOM and a 9 or 10mm carbine. If the liberals don’t screw it up I’ll build those and be done.

    3. avatar Someone says:

      7.62×39 is better than .300 blk in AR15? Maybe, but for what? Advantage of .300 is in wide bullet weight choice, good speeds out of short barrels and that the only change vs. 5.56 is a barrel (might be a disadvantage if you mix up your magazines).

      1. avatar No One Special says:

        Actually yes! First and foremost more availability and cheaper ammo are the biggest two reasons. Another is ballistics. For 154 gr for the 7.62X39 and 150 gr for the 300 shows the 7.62X39 wins out at about 150-200 fps. Accuracy isn’t even a talking point since I have yet to see or shoot either that is capable of what I call accurate. That being no more than 3/4″ at 100 yards. Which is why I don’t own either one. The biggest reason for a 300 blackout is for suppressor use which I already stated. However the 7.62X39 can be loaded down with heavy bullets as well. At one time that is what everyone had to do before the 300 blackout was standardized. They loaded the wildcat 300 whisper for what ever end result they wanted. All the 300 blackout did was make it easier for people that wanted to play and didn’t want to load their own ammo. Which is something else that amazes me. I may not save money by loading my own ammo but it more accurate and I shoot a hell of a lot more for the same money.

  7. avatar pwrserge says:

    Meh, I just finished rolling out my take on a 18” 5.56×45 SPR and I’m honestly not impressed with the specialist chamberings floating around out there. Sure the 6.5 Grendel guy can ring steel a bit more effectively than I can with my mk262 IMI ammo at 600 yards, but if I need to run and gun a shoot house at sub-30’ range, I can just pop in a magazine of m193, dial my scope back to 2.5x and I’m good to go. Need barrier penetration? Pop in a magazine of 75gr SP and I can reliably engage targets behind intermediate barriers. Need to pop steel at 700 yards? Dial my scope up to 20x and I can reliably ring IPSC steel plates because I have a handy dope card on my stock in 100 meter increments. At the end of the day, even my “premium” ammo comes in at ~$.60 per round. That counts for a lot when you practice with a dueling tree at 200 meters.

    Summary: while specialist chamberings can do specific things better than 5.56×45, the versatility in loading and far lower costs of 5.56×45 easily make up the difference.

    1. avatar Dan W. says:

      My SPR build does so much so well I haven’t been able to justify much else. Pop in a 22 conversion for close range plinking. Can’t do that with any other calibers.

    2. avatar No One Special says:

      The 6.5 Grendel and 224 Valkyrie will do everything the 223/5.56 will do and more times than not do it better further. Plus if that isn’t a good enough reason to have options than there’s the best one of all, America. I own both 5.56 and 6.5 Grendel plus 6.5 Creedmoor in an AR-308. Like them all and wouldn’t want to be without any of them. As for social work I would have no problem using my 6.5 Grendel. The 123 gr MatchKing is a nasty little pill that would make short work of 2 legged vermin.

      1. avatar Wild Bill says:

        224 Valkyrie. You mean the crash and burn caliber of 2018.

        1. avatar No One Special says:

          Actually I believe that was the 22 Nosler. There are far more people shooting 224 Valkyrie and for good reason. I in no way said the 223/5.56 doesn’t have it’s place. What I am saying from experience the 6.5 Grendel and 224 Valkyrie from the AR platform will do everything that the 223/5.56 can then some and many of those things they can do better. It’s not personal it’s just the plain simple fact of performance.

        2. avatar pwrserge says:

          I’m going to call you on the “everything” claim. Grendel has a significant increase in recoil impulse when compared to 55gr garbo tier blaster ammo. Sure you’re not going to punch cloverleafs at 300 yards with it, but for clearing short range stages, recoil recovery matters far more than a slight increase in weight down range.

          You’re right that each of the rounds discussed out-performs 5.56×45 in at least one area. The reason that 5.56×45 isn’t going anywhere is that none of them outperform in ALL areas. A .223 Wylde chamber is the ultimate intermediate cartridge example of “jack of all trades, master of none”.

        3. avatar No One Special says:

          The reliability issue isn’t an issue these days provided quality parts are used from reputable manufacturers. If a rifle is put together with parts that are befitting the chambering the perceived recoil impulse from 5.56 to Grendel is negligible at best. This is of course shooting heavy for caliber bullets from the 5.56 70 gr+. Like I said elsewhere I don’t shoot anything lighter than 60 gr in 5.56 and that consists of 2 bullets primarily. One being the 60 gr V-Max and the other is the 65 gr Sierra Gameking. If the nonexistent reliability issue is of such concern buy a high pressure bolt from Anderson, JP, or several other manufacturers. I can’t shoot all of my guns either in one range session but I can shoot them enough in the year to justify having them and more. Lastly a barrel is like tires on a vehicle. If you drive it you accept the fact you will need new tires at some point. Same with a rifle. If you shoot it you accept that it will need a new barrel at some point. If replacing a $300+ barrel is out of reach than the rifle itself was probably out of reach too realistically.

      2. avatar pwrserge says:

        I shoot enough that shooting out barrels with .224 is a serious concern. Especially on a precision rifle build where you don’t get much peak performance barrel life to begin with. Add that to the absurd ammo cost for regular practice and high round count stages, and the scales start to tip. Combined with optics, that rifle easily crosses the $5k mark, I’m not in a hurry to start dumping money into a burning dumpster just to feed it or be cost constrained as to shooting it.

        I’ve discussed my issues with 6.5 Grendel in another post. To me the higher cost of ownership combined with a lower mechanical reliability due to shoddy design choices make it a no-go.

        I own 3 rifles that I shoot with any regularity.
        – my go-to general purpose take on a 10.3″ Mk18
        – my take on improving the M4 carbine (down the the 14.5″ barrel and M4 Calibrated ACOG)
        – my mid to long range SPR (the rifle discussed above)

        I’m not in a hurry to add another gun to the pile sitting in my safes that I never get the time to take out and shoot.

  8. avatar Blue says:

    The .224 Valkyrie may pull me away from the 22-250

    1. avatar Rswartze says:

      I don’t have 22-250, but I do have an AR in 5.56, 300BLK (10.5″) and .224 Valkyrie. I just grabbed a PSA 224V upper and slapped it on my nice trigger lower. Never went through 20 rounds of factory ammo, bought new brass and 500 of the Hornady 88gr ELDs right up front. Only about 250 rounds downrange, but I’ve got sub MOA groups at 600yd in slight wind that were the highlight of my summer so far.

  9. avatar former water walker says:

    I’ll keep my lowly S&W Sport chambered in 5.56 & 223. I’m 65 and not bored at all…

    1. avatar Art out West says:

      Sometimes “lowly” is lovely.

      I shoot my Marlin 60 far more than my AR. Then again, I’m not a tactical badass operator. I just enjoy shooting.

      1. avatar LazrBeam says:

        +10. Same here except instead of Marlin 60 (although I have one) it’s an old Remington Nylon 66 or a 10/22.

        1. avatar Art out West says:

          The old Nylon 66 is pretty cool. I have a bunch of 22s, but lack the Nylon 66.

        2. avatar DesertDave says:

          I had both a semi and lever Nylon in Apache black when I was a kid. Dang I wish I still had them. The lever action was my favorite.

      2. avatar Ransom says:

        Love the model 60. More so now that .22s are plentiful and affordable again.

  10. avatar American Patriot says:

    Change is good…..That’s what obummer said, I’ll stick with my 5.56 & for ea 100 rds of the other stuff you mentioned I can get 200-400 rds of 223/5.56. I have lever & bolt guns for the bigger bores.

  11. avatar Dbag says:

    Come on, dude. 47-70 Govt is .458, not .452.

    1. avatar PlinkrBlaster says:

      Dbag beat me to it. This article needs to be corrected.

  12. avatar Esoteric Inanity says:

    “By contrast, .450 BM is a necked-up .284 Winchester with a .452-inch projectile, the same as .45 ACP, .45 Colt and .45-70 Gov’t.”

    Seriously? What reloading manual has Sam Hoober been reading to conclude that a 45-70 Gov is loaded with a .452” bullet? Also, not to be pedantic, but the .450 BM is derived from the .45 Professional, which was itself, a necked up and shortened .284 Win case.

  13. avatar Rad Man says:

    More compact, lower weight rifle, countless accessories, compatibility with available web gear, etc. Perhaps the bolt issue will come to bear but I’m not aware of too many issues when the bolt and barrel were properly matched.

    1. avatar pwrserge says:

      I have never seen a 5.56×45 rifle go down due to shorn locking lugs. I have seen that happen twice with Grendel rifles. Given the fact that around here, Grendel rifles are absurd unicorns, that’s not a good thing. Anecdotal, yes. But not a good data point. I think to run Grendel reliably, you need to redesign the bolt and carrier from the ground up. You could probably do it while sticking inside the AR15 footprint, but retroing a standard AR bolt by changing a couple of last second milling steps has proven to be a problem. Nothing wrong with the round as a whole, just the way it was implemented.

      On a side note, not sure how much you really pick up over 5.56 for practical social work purposes.

      1. avatar Rad Man says:

        Double the bullet weight with a plus .500 BC, traveling at over 2700fps. Theres some KE and effective range gain there. Mag capacity is reduced to 25 rounds.

        1. avatar pwrserge says:

          I haven’t seen a 154gr 6.5 Grendel loading. The ‘ole 5.56 round gets a lot better when you move out of 55gr and 62gr garbo ammo and into serious high-performance loadings. (Which can still be found cheaper than most Grendel food) True, the Grendel still does better, but is it enough better to justify the increase in cost and decrease in reliability? To me? No.

        2. avatar No One Special says:

          Reload for the Grendel and the cost is a wash to me given the added performance benefit. I don’t have reliability issues with my Grendel or any of my AR’s for that matter. Although I put each one together from stripped upper and lower receivers. The lightest bullet I shoot from the 5.56 is 60 gr V-Max and that’s for hunting purposes. Everything else is 70 to 77 gr and that’s because the heavier bullets in 5.56 perform better. Cost and reliability are not really viable concerns these days if you are comparing quality ammo for both chamberings. Now if it’s cheap pinking ammo that’s another story.

        3. avatar pwrserge says:

          I regularly shoot short range stages that don’t justify a 77gr pill. Most competitions I go to have 2 short range CQB stages and a medium (100-200 meter) stage. When you shoot m193 out of a DMR, the recoil impulse is effectively non-existent. As for reloading… Lol… no. I don’t have anywhere near that kind of free time.

        4. avatar No One Special says:

          After initial set up of my progressive press for the cartridge being loaded I can load 200 rounds in about 30 minutes. Most people waste that much time on things like Fakebook that are less productive. The end result isn’t near as fun either. Priorities vary from person to person. Life priorities not withstanding. I have a home and family and other responsibilities too that doesn’t limit my availability of time.

  14. avatar GapharmD says:

    I own all of these calibers (suppress all of them) and they are great but Grendel and Valkyrie have better applications than the socom.

    Let’s be honest if you going big game hunting your not bringing an AR-15. Ar-10….. maybe…depends.

    If you haven’t got in the suppressor game, you are missing out. Changes you entire shooting/hunting word.

    1. avatar pwrserge says:

      Sadly, a large number of us don’t have a choice.

    2. avatar No One Special says:

      I hunt with 6.5 Grendel and 6.5 Creedmoor for whitetail both in the AR platform. I want to get into an SBR and suppressors but giving the government $200 to play rubs me the wrong way.

  15. avatar BeoBear says:

    I’ve been shooting the 6.5 Grendel for several years and it’s a much better choice than the 6.8 spc. There’s nothing wrong with the SPC it just doesn’t have the capability of the Grendel. Factory Grendel ammo is being offered by more and more manufacturers and is found just about everywhere these days. The bolt issues haven’t been an issue for a long time. They make excellent hunting, defense and long range target shooting multi-taskers.

    The .50 Beowulf is as good or a better choice to the SOCOM. The big bore AR’s all accomplish the same thing, it just comes down to details and preferences. I like the Beowulf because there are tons of .50 bullets available for reloading and factory ammo is quite a bit cheaper than the other two. Plus I like having a “fitty cal” AR15. It’s fun to shoot and everyone wants to check it out at the range.

  16. it does make me wonder about the 30AR remmington. you know that really short lived rifle they had when they bought out bushmaster and put their name on the rifle and had their own 30 cal round for it. what ever happened to it. I know they bailed on it when some shithead working the the domokraps did another shootout but I wonder what the round would have been capable of with different loadings. and hey if it is still out there then I am sorry but I just don’t see it. but it might have been better then the 300 blackout.

  17. avatar AlanInFL says:

    I am surprised there were no mention of 9mm or 6.5 Grendel as an option.

    Then again 7.62×39 was not listed either.

  18. avatar Kevin says:

    I have an AR in every caliber mentioned above…not because looking for something better…just different. I can tell you I do prefer an AR pistol in either 300blk, or 9mm for home defense. When just wanting to shoot a lot of rounds you can not beat the 5.56/223, 7.62×39, or the 9mm. You can shoot all day without your wallet helping at you. Long Range shooting is your game…224 Valkyrie, 22 nosler, 6.5 Grendel or 6.8 SPC are good choices… Hunting mid size game like whitetail deer… I prefer the 6.8 SPC, however I will be using the 350 legend this year. I typically use a Marlin 336 30-30 when hunting the brush. This year I will take the legend… If you are a gun guy/gal or not… The AR is just a great platform to try something different with expensively compared to other platforms. (Lever / bolt actions)

  19. avatar Gov. William J Le Petomane says:

    Funny how the 19th century .30-30 delivers more energy at 200 yards than the ‘tactical .30-30’ does at 100 yards.

  20. avatar Adambomb286 says:

    I bought a WASR 10 back on ’05 or so when that was the cheap option for a semi auto. I recently sold it because I wasn’t using it and needed the cash but now I’m looking to buy my first AR. I will probably end up with an AR in 7.32×39 and I really want it to be a side charger so basically an AK with a better optics mounting system and a less reliable action. I plan on using it for hunting so I have this idea of a universal do-it-all AR where I can swap the upper and magazine and shoot .410 for small game, 7.62×39 for plinking and WV whitetails, .223 for groundhogs and varmints.

  21. avatar Matthew Huesmann says:

    I really like the 224 valkery. That’s been a good round for me. Real accurate and catching on in popularity.

  22. avatar Paelorian says:

    In terms of external ballistics, clearly the best cartridge that can be shot out of an AR-15 is 6mm Grinch. Or the essentially identical but less snappily named 6mm AR Turbo 40 and 6mm FatRat. The main difference is who you buy your components from. They’re all 6.5mm Grendel necked down to 6mm and with the shoulder made steeper through fireforming Ackley Improved style for more powder capacity. The result is a cartridge very similar to the best large-frame AR competition cartridges like 6mm Creedmoor or 6mm Dasher, just a little slower. Shoots the same 100gr+ bullets accurately. .243 Winchester is also similar but won’t fit in standard detachable magazines with the longest, most desirable bullets. The slower, non fireformed simply necked down versions of these cartridges are also very good (6mm AR, 6mm Rat).

    So it’s possible with these rounds to shoot 105gr 6mm bullets at around 2900fps out of an AR. In typical use it will probably be a little less, of course. These are ideal AR-15 cartridges for competition and military use, and also excellent for hunting game up to the size of deer. Though more powerful 6.5mm and 7mm rounds are more versatile for hunting medium and big game, they won’t fit in an AR-15 without severe compromise in external ballistics because no AR-15 cartridge can push the best 6.5mm and 7mm bullets to the speeds at which they perform best in flight. But the AR-15 can just barely launch 6mm bullets to speeds in the ideal velocity range. Long range excellence with mild recoil so that short range performance isn’t much compromised. And close in it packs a wallop, bordering on being either a very powerful intermediate cartridge or a very weak full-power rifle cartridge.

    No, you can’t buy the ammo at your local gun store. It’s a wildcat round for handloaders. It may not be the most practical choice for your use. That doesn’t mean it isn’t an ideal AR-15 cartridge. It’s definitely the best performer at long range.

  23. avatar Texheim says:

    Ha, I have all three of these and a 6.5 Grendel.

  24. avatar dwest says:

    Beowulf.

  25. avatar Timothy V Noecker says:

    What Would a AR-15 Chambered in .243 Winchester Hold Capacity Wise?
    I’d Love To Have One If Available…

    1. avatar No One Special says:

      AR-10 or AR-308 large frame with LR/SR25 magazines will hold 25 rounds. With standard magazines 20 rounds max.

      1. avatar No One Special says:

        React the AR-10, The LR/SR25 magazines will not work with the AR-10.

  26. avatar T says:

    This article is a joke. 6.8 is dead. 6.5 Grendel is going strong. Any beginners taking this as informative in 2019 is being misled.

  27. avatar Lowell Vincent says:

    lengthen 9 mm to magnum. straight wall hunting charmer. capacity stays good.

    1. avatar Kenneth C Hinchman says:

      I have the 9mm Winchester magnum (9X29.5) in an AMT Auto mag III that I am forced to reload for as almost impossible to find factory loads. I agree is would be an interesting round for a carbine.

  28. avatar Ben S. says:

    6.5 Grendel is my favorite -15 caliber so far, and I like trying new calibers. I’m sure the BHW 6.8-based wildcats will grow on me when I actually make some brass and get them dialed in, but that’s the thing: you can’t buy factory ammo for a wildcat, so they usually languish among the general public. I’m also looking forward to trying some deer hunting with my new 7.62x40WT soon, but honestly, the wide open countryside I have around here is better suited to the long-legged Grendel anyway. I have two 16″ Grendels, and a 24″ upper to use for the range or possibly PRS in the near future. Gotta say the 16-incher’s are more fun to shoot and easier to carry around. I still have no trouble at all smacking steel with boring regularlity at 600 yards with them. The Grendel is what I recommend now to anyone who has an AR and wants a more potent round that’ll basically do it all- at least as much as the smaller, lighter AR-15 platform can possibly do.

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