Any interest in the 6.5 Grendel?

I'll just leave this link here, was going to avoid linking to another forum, but perhaps someone might like to see what actually has been done and a rifle that is apparently, so far, completely functional in this caliber with its magazine. The 527M doesn't need any different magazine, either, for 6.5, from what i am told, BUT, i have zero direct experence with this round, so I'll leave this last bit here and let the experts hash it out.

http://www.czfirearms.us/index.php?topic=75875.0

What about an RPD? Grendel fits the links just fine (just sayin')



And this thing that also showed up in the image search, which at least looks like the coolest thing ever, even if highly dangerous to bearded tier-one operators

VZ58's can be easily converted to take AR mags, ergo Grendel mags (assuming one cannot adapt an AR mag themselves). The things are like 20$, so assuming they are actually available (haven't tried to buy any yet, obviously) it's not a monstrous proposition. Kinda silly to expect AR-mag commonality in such a different caliber though (definite point for 223 cases, but it's not like all of us are stocked up on AR mags in the first place). To be honest, I was planning on modifying Galil mags so as to preserve rock/lock function which I care for (or Mini 14 or 223 AK or any number of similar designs)

From what I'm reading, a big portion of the reason the mag-feeding is so problematic is due to there being exactly zero room left in the magwell for the ammo to get started before hitting the feed ramp; I have to wonder if one used a roomier mag or action (HK being the extreme example) whether the angle of presentation might be less of an issue

generally speaking the bolts in just about every other rifle you could chamber 6.5 grendel in would hold up just fine, bolt actions, AKs, SKS, VZ58, galil ace, sig 556r, PTR32, if these all had barrels chambered for it you could bet theyd handle the pressures just fine.. however all those magazines that go with those rifles are useless because alexander decided to make a cartridge that wouldnt work well in the AR, but still decided to pander to it enough that it cant really be chambered in anything else either..

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I don't think we can honestly say for certain the Grendel isn't also hard on SKS's or VZs simply because the experimentation is still so limited; they certainly aren't going to be as durable as the AK or PTR, which we all know are rather stupidly overbuilt to start with in the bolt area. We do know that all those guns don't use nearly as hard/brittle a metal for locking surfaces, which should be beneficial from a fatigue perspective, and have meatier parts supporting the smallish locking surface areas (so maybe not as much deflection/fatigue right at the locking lug, making bearing the critical failure mode rather than fatigue as in the AR bolt --possibly raising the acceptable bolt thrust value above the AR in doing so & making Grendel more palatable)

Definitely worth trying, of course, and I intend to at some point. Considering the ballistics & gas action, it'd be a sort of miniature SVD, come to think of it . 'Course, I'm also still dreaming on a drop-in belt conversion for the VZ58, in which case that RPD belt may be more practical than box magazines as it'll work for both Grendel and x39

***Come to think of it, I have a barreled action for a VZ52 rifle not doing anything (planed on a PPSH-looking build using the stock from an MGS kit). Quite frankly, the x45 looks like it's almost straight enough, and certainly long enough, for the standard magazine to run, with an extra .1" breathing room no less. x45 is a really cool cartridge in its own right, but I'll bet any of the modern 6mm's beat its drum in most respects. The knock-off Garand trigger is probably easier to tune up for accuracy than the VZ's striker-squish, also

7.62x45 is apparently rated at 60ksi (yipes; didn't realize that thing was so fiesty, seems suspicious) which would mean it's plenty strong enough...

TCB

I've been shooting a Grendel for a little over a year with absolutely no problems. Mine is a 24" AA, it's excellent for deer and pig hunting, but I've only shot it to 600 yards at the range so can't comment on the long range capabilities.

hmm, a bullpup RPD, thats something i havent seen before

24" Barreled 6.5 Grendel in the AR Platform

I wish I had known the 6.5 Grendel was such a poor choice for a conversion, just kidding, I have shot a good bit through mine with zero problems, I reload for it and using the data from multiple sources and TAC powder I am getting 2525fps at the most for muzzle velocity, and .510 BC is not that terrible for a low to no recoil rifle. I have had zero problems out of the magazines either, I bought those from Midway for the 6.5 Grendel, I have 2- 5 round magazines a 10 round and 1-15 round magazine and all feed excellent. I have not been getting to the range as much lately because it is being redone, I intend to keep shooting and enjoying the lowly Grendel upper on my AR15. I will run it til it breaks.

hmm, i wonder what it would take to fab up some AK style mags for 6.5 grendel, i could make the magazine bodies out of sheet metal, use standard magazine springs, the followers i guess would be the hard part

Well, you'll need to develop & machine a set of male/female dies for each half of the magazine (expect at least half a dozen iterations of trial & error unless you're an experienced tool & die guy, in which case like three). That by itself is enough of a hurdle for no one to have met success that I'm aware of, apart from some very high dollar custom shops like the FG42 guys. Followers are comparatively easy (i.e. printable/carvable for testing). At least the floorplate would be straightforward. Good luck.

And that's why AA bothered with the AR mags (granted, now that he has found market success, it kinda begs the question why he isn't paying to have AK-specific mags made) way back when they were getting started. Either that, or try to sell customers on an expensive permanent mod to their AKs so they could have more effective ballistics past 500yds

TCB

thats the cheaper and easier way to make magazines IF youre doing it on a massive scale.. other methods could be used that make it cheaper and easier on the smaller scale.. you could make a magazine body out of four pieces, two sides, and a front and back bent to the contour of the magazine, cut and fold over tabs that get spot welded to the side plates which also contain the feed lips and the slot for the floor plate

rollers can be made by bending a sheet metal box out to fit the inside of the magazine, riveting in axis pins underneath rollers that have been lathed down to the taper of the rifle cartridge (this is how sterling SMG followers are made).. this technique would be cheap and easy on a small scale, but of course more expensive than stampings on a mass production scale... im fairly confident reliable 6.5 grendel magazines could be made inexpensively if one knows how to do a little sheet metal work

i dont hate the 6.5 grendel at all, i think it has potential to be a great cartridge, i just think alexander was an idiot to pander to the AR as hard as he did and essentially curse the whole project

"...this just proves what ive been saying all along..."

Sorry...does no such thing. There are real, full-time competitors who use/reload thousands of rounds for practice/competition each year because the load is inherently accurate..and I'll trust their actual experiences in a loading which has killed more moose than any other caliber known to man.

6.5x55mm is a superior hunting cartridge because of its exceptional BC and velocity. If you can duplicate that in an AR platform, why not?

Blade First said:

6.5x55mm is a superior hunting cartridge because of its exceptional BC and velocity. If you can duplicate that in an AR platform, why not?

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The only AR you're going to duplicate 6.5x55 in is an AR10 running either 6.5 Creedmoor or .260.

It's really amazing how much fantasy nonsense comes attached to the 6.5 Grendel. I guess that's what happens when you have a cartridge made by people ignorant of ballistics and driven by marketing to the same.

Creature said:

Llama Bob, thank you for your copious input, but enough is enough.

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You don't get to say whether I post or not. Sorry. Nice try though

OK. I don't like people spreading misinformation about guns, especially when they do it in a dangerous way. And dangerous is exactly what you'd get trying to come even close to 6.5x55 using 6.5 Grendel in an AR15. You may think nothing needs to be said about that, but I disagree.

what llama bob says is right, if you dont want to hear the facts, thats not his fault or problem. 6.5 grendel and 6.5x55 both operate in roughly the same levels of chamber pressure but the 6.5x55 clearly has significantly more case capacity and higher muzzle velocities using equal bullet weights.. 6.5 creedmore can match x55 ballistics in a shorter cartridge by using higher chamber pressures but there is no world, no alternate dimension where 6.5 grendel will EVER come close to 6.5x55

that said its not saying the 6.5 grendel is a bad round but you have to accept it for what it really is and not for what you want it to be, its not going to outmatch anything in the AR-10, its not going to bed 308, but what it will do is achieve the barrier penetration and muzzle energy properties of 7.62x39 in a much flatter shooting cartridge that will deliver larger wound cavities as the bullet tumbles (since damaged caused by tumbling relies almost entirely on the length of the projectile)

the belief of 6.5 grendel being as good as a 6.5x55 or one of its equivalents should go in the same round file as "30-30 performs better than 7.62x39" and "5.7x28mm is a good self defense pistol cartridge"

I was once squadded with Mr Alexander when the Grendel was new. I wish I had known more as I would have asked him design questions.

I know shooters using the 6.5 Grendel as a target round. I think they are using single stack magazines. For a couple of them, they had have a period in which they were sorting out magazine issues. The case is very straight and I don't think it is very tolerant of out of alignment issues. One shooter, his gunsmith supplied an extra bolt, for the time when the first bolt cracked its lugs.

If you want something to play with, well, why not a Grendel? For all the crazy SHTF stuff, I would go with an AR15 and 75 or 77 grain bullets. I have shot the 75's at 600 yards and they are wonderfully accurate and I think, still supersonic. Six hundred yards is a long darn way and people who think they are going to hit tea cups at 600 yards need to get out to the range and try. A little wind blows the bullet a long way. Of course the 6.5 mm bullet is better ballistic ally out to 600 yards. But past that, forget it! This is the primary reason the NRA service rifle rule was changed. The AMU and All Guard were struggling at 1000 yards with their match 223 rifles against civilians shooting M1a's and Garands. I have pulled 1000 yards targets with a 223 shooter on my target and you can't hear the bullet, it has gone subsonic. I have been told reports of 223 bullets not going through the cardboard at that distance! Anyway the AMU got the rules changed so the 308 Win AR10 is a "service rifle" and they are back to cleaning up the individual and team matches at 1000 yards.

I was interested for a little while a couple of years ago. Back then the components to build a 6.5 were a couple hundred more than those I could get for a 6.8. I ended up going the 6.8 route on the basis of cost since I have little interest in long range target shooting. Not sure if the cost differential still exists or why, but I guess it is just a supply and demand sort of thing.

ive been contemplating designing my own .277" caliber on the 7.62x39 case head and preserve the taper for AK/VZ/SKS magazine compatibility.. results? 110 grain projectile with BC of .370 with a muzzle velocity of 2675fps from a 16 inch barrel, or 2535fps with a 120 grain SST with ballistic coefficient of .400.. the 110 grain would match the drop of the 123 grain 6.5 grendel at 700 yards, it would be flatter shooting inside this distance and it surpasses 6.8SPC

so if i was going to make anything on the 7.62x39 case i might go that route, at least then its just a barrel swap from any 7.62x39 rifle to convert or i would start out on the 12mm case head and basically neck-down 7.92x33 with a longer COAL since reloadable 12mm/308/30-06 brass is so much easier to come by than 7.62x39 brass or grendel brass

ive been contemplating designing my own .277" caliber on the 7.62x39 case head and preserve the taper for AK/VZ/SKS magazine compatibility

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Supposedly the Grendel was exactly this at one point (I suspect very early on, when it was basically a necked-down, set back x39), but the the whole "x39 in an AR" thing hadn't been sorted out yet.

Think about it; you've just designed a new intermediate cartridge optimized for ~500-700yds accuracy (only regime where it's distinctly different enough from the competition to be worth the trouble), and now you've got to market it to owners of SKSs and AKs. A rather expensive & intensive permanent operation, also. Talk about your fireproof paper hat. I know that both platforms can be made accurate with proper care, but long range shooting is not what they were built for, not what they've come to be known for, and not what many are even capable of. Surely not what most owners are expecting, compared with ARs or M1As. He was on the right track choosing the x39 case head, as it's the next larger diameter from 223 but still super cheap and ubiquitous like 223, but I think a couple years ahead of his time in that there weren't good 7.62x39 AR options around to grow off of.

However, by straightening the case so as to be usable from AR mags (albeit with modification, which I would love to see the details on; I suspect it ain't much) your hot-shot sniper cartridge is now easily usable from one of the most consistently accurate platforms available. Marketing practically writes itself, at that point.

So to say it was a mistake to 'pander' to the AR is very short-sighted; the 5.45,5.56,6,6.5,6.8,7,7.62,8,9x39 cartridges have all existed for a very long time, yet not one of them got very popular in rifles not initially chambered for it (and even then, only two of all those calibers). It's simply too expensive, difficult, and permanent a proposition for most folks to experiment with their AKs like they do ARs. Now, AA could have instead pandered to the AR10 size platform, but considering the whole point of Grendel was a step DOWN from 308 (size/recoil/muzzle energy but not trajectory) the marketing was just as unrealistic as for the AK. And any sort of hybrid AR10/AR15 or AR47 type thing to get a stronger bolt in a small package was wildly beyond the scope of the project.

It would seem the homesmith tinkerers are interested, though, since there were apparently VZ52, SKS, and a whole lot of AK barrels in Grendel sold in recent years. Sadly, the way most homebrew tinkerer parts-makers run their businesses, it is likely those barrels are still yet to be completed, but it remains clear there is a lot of interest in the Grendel in non-AR platforms at the cutting-edge of development. I think whenever the RDB comes out in Grendel it will be a huge success.

To be honest, I think it'd be worth exploring whether a taper between the 223 and x39 might be compatible in both after very minor follower/feed lip adjustments (if that). I suspect Alexander's needs were more urgent at the time, so the 223 taper was chosen as a 'sure thing' to proceed on, otherwise more experimentation with cross-compatible forms may have been done. But still, with the various AK-mag AR lowers, x39 AR magazines, and AK-STANAG conversion kits available now, it's kind of a moot point. At least with a straight taper you get another grain or two of volume

110 grain projectile with BC of .370 with a muzzle velocity of 2675fps from a 16 inch barrel, or 2535fps with a 120 grain SST with ballistic coefficient of .400.. the 110 grain would match the drop of the 123 grain 6.5 grendel at 700 yards, it would be flatter shooting inside this distance and it surpasses 6.8SPC

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That actually sounds a lot like SPC, itself (or is it PPC? Talk about confusing), only with enough extra case volume to make up for the slightly-worse BC of fatter bullets vs Grendel. Just don't go trying to duplicate 7mm Mauser performance, or anything (kidding, of course; it's exactly analogous to trying to duplicate 6.5 Swede from Grendel, or heavy 30-06 from 308 for that matter --there's a time & place for each, and far downrange the only determining factor is how heavy your bullet needs to be since the trajectories are similar). Only other thing to keep in mind is recoil, at least as a sanity check; Grendel already has about 2/3 that of 308, so pushing bullet weight or velocity much farther in a much smaller/lighter firearm will be self-defeating to a certain extent. That's why I am glad to hear that Grendel is apparently at its most consistently accurate a step or two down from the max load spec for most bullets; puts it even more squarely between 223 & 308 but with a trajectory & long range ballistic effect much more towards the 308 than 223.

The main thing I like about Grendel and similar cartridges is that I think they could provide the basis for a realignment of our NATO catridge set that ends with our infantry having more capabilities at the end of the day. Bumping 5.56 up a skosh from the very bottom-end of 'intermediate cartridges' would give ample justification for bumping 308 up a bit to something more truly effective past 1000yds for LMGs, be it Creedmore or even 300WM. These larger rounds are sufficiently big to not be tempting for a standard rifle platform (except perhaps Creedmore). And lastly, since the power gap between the service carbine round & pistol round will have widened, it becomes more practical to consider something like a PDW to supplement the pistol set for those not actively engaged in pursuing the enemy but who would be better served with a long gun (meanwhile pistols become shrunk to more useful concealable size rather than the honkin and mostly unused hoglegs they are now). Specific-size rounds are used in specific types of guns for specific combat roles, and there is less temptation to use weapons for improper roles (i.e. M240 in a tight apartment sweep vs. an SBR 5.56 or 6.X, or a slung PDW for busy mechanics vs. a small pistol on the belt)

TCB

its not short sighted to say they pandered to the AR, because they took the taper out making it incompatible with 7.62x39 rifles almost entirely, only so it would fit in the magazine well of a completely different rifle that lacks the adequate enough bolt strength to handle it... the short sightedness came from alexander with that move

and that said, the AR is full of cartridges of competing rolls, 6x45mm, 6.8SPC, 7.62x40WT, now you have a bunch more.. all these options on top of the problems the grendel has has lead it to be a very poorly received caliber.. had the taper remained youd be seeing very large numbers of AKs, SKS, and VZ58s chambered for it

Another 150 rounds through my TYPE I (unmodified 7.62x39 in 9310) 6.5 Grendel yesterday. Hitting targets @ 500 yards.

Takes my round count past 2500, no broken lugs. It is amazing what can happen when you move from the theoretical to the practical. Maybe there was something out of spec with Llama Bob's and justin22885's faulty 6.5 Grendels? Oh right, I remember, they don't have 6.5 Grendels...

Been kicking around the idea of building a 6.5 upper for a while. Main purpose would be ringing steel at long range and shooting wary coyotes that don't want to come inside 4-500 yards. I like the .223 and have a mossberg MVP that's a tack driver with 50 gr vmax, but the high BC of the 6.5 makes me want to go that direction, along with the fact that factory ammo is becoming more affordable and available.

had the taper remained youd be seeing very large numbers of AKs, SKS, and VZ58s chambered for it

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Which comes back to my point about the marketing; why the heck would any AK/SKS/VZ owner be interested in a long range performance cartridge, considering the guns are not consistently capable of the needed accuracy, nor easily scoped to utilize it, and the switchover would require a likely months-long surrender of the weapon to a gunsmith --all in pursuit of the promises of a new, experimental cartridge. 'Twould be no buyers, and the round would have died off long ago.

It made no sense to offer the round as anything but an AR upper, or maybe a turn-bolt (AA should have gotten a CZ distributorship ). I should think that's obvious. What's less obvious (especially at the time) is how maxed-out the AR15 bolt is as-designed, which ultimately makes this whole notion of a search for a more powerful cartridge for the platform a bit foolhardy. Again, it can't be emphasized enough how much more knowledge there is about the AR platform than 8-10 years ago when the round was being developed. The 7.62 case head is a decent conceptual compromise between the diminutive 223 and the far larger 308 (which just barely-barely fits the bolt without breaking through the fence on the bolt face).

Speaking of which; anyone got pictures of these broken bolts? I have a theory about how they may be failing, and it has less to do with bolt thrust than geometry. Sadly, the one picture I found doesn't have a very sharp close-up of the fracture;

I suspect the super-narrow fence may be acting as a stress riser/crack nucleation point, which then propagates down through the lug to failure. The bolt bows inward like a diaphragm ever so slightly when loaded, and the forward extension of the lugs past the bolt face rock inward against the fence a tiny bit. The increased bolt thrust amplifies this, but not nearly as much as the reduction in strength of the fence after it has been opened up for the larger case head. It sounds counter intuitive, but you might actually get better fatigue performance by removing the fence from between the lug tips; we run into this kind of situation all the time in aerospace where less material actually yields a stronger part (from a fatigue perspective; less material is always weaker in absolute terms). Were the crack started at the lug root as we suspect, you'd expect to see the crack propagate across the meaty part of the bolt more. I'd also love to see an MPI test on a broken bolt, to see if there are other cracks present; if it's just one, to me that suggest manufacturing faults rather than pure fatigue/overload as the culprit (it's not like anyone ever passed off cheap-metal AR bolts before )

Also, stupid question; why don't they just make the lugs longer, and unscrew the barrel extension a few turns? You never hear of extensions failing, and the bolt lugs themselves look like they got trimmed a good 1/8" shorter than the casting during manufacture.

There's a wildcat round called 510 Reedwhacker, which is WSSM brass cut back to the shoulder and fitted with a ~425gr slug and enough powder to reach low-end 50 Alaskan loads. Lotta skepticism at the time from folks who were freaked out by the bolt face breaking past the fence entirely (bolt head looks like a tower parapet), to the point an FEM was run, and found the missing material had no significant impact on load capacity (I think pressures were around 40ksi, but with the wide breech face bolt thrust went up a bit & ate some margin, same as with Grendel). Granted, the recoil of the round as well as cost limits the volume of shooting, but I believe the first bolt in the AR15 (other conversions had been done previously) is still doing great many hundreds of shots later (not sure if they're past 1000 at this point)

Just saying that things are not always as immutable as they seem.

TCB

BTW, it's not a bad idea to keep a small vial of iron filings around to do your own 'MPI' testing in general. Whenever a crack forms, the two halves develop a slight magnetic couple (N/S poles) which will attract ferromagnetic shavings/particles. Frankly, on any gun, it wouldn't be a bad idea to do a quick check on the bolt lugs every thousand rounds or whatever. They do the test in case cracks occur during the casting or forging that are exposed by the machining operations, but there is no reason they can't form later on when cycled under load. By the time your eye can see a crack in something as hard as bolt-steel, it's already propagated completely to failure and is spread apart into a gaping chasm as far as the part is concerned; MPI can catch the cracks while they are only at surface-level (sadly, I think only eddy-current testing can catch stuff under the surface) and are not yet grossly effecting part strength.

Just be sure to clean the filings off well when you're done

TCB