308 vs 6.5 Grendel vs 6.8 SPC

I would say 6.5 but... Bill A. came off like a tool every time he posted on another forum. Also, there are guys on a certain 6.8 dedicated forum that have killed deer at just over 400 yards. And for hogs it IS the bomb.
From personal experience the only unreliable 6.8 was a bad batch of 90gr tnt from SSA that was over pressure, and recalled. Primers in the action lock up an AR pretty quickly.
If you do go that route I highly recommend 85gr TSX. Incredible expansion and scream along at 3000fps so nice flat trajectory.

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If you mean Bill's attempts to keep the chamber & ammo specs somewhat proprietary early on, there's a good reason; given the amount of testing he claimed to have done, he was likely quite aware that he was operating near the limit of the AR15 bolt's capacity, and wanted to eliminate as many variables as possible during the early period of the chambering's introduction. Hence why he required (free) licensing for reamer & barrel makers, to try to ensure the product they were selling was actually compatible with his Grendel specs.

Wasn't exactly a bad assumption, either, given how LWRC went and did a knockoff cartridge that tweaked the original design to use standard 7.62x39 bolts with weaker extractors, against his wishes, while AA's supplies were backlogged. It wasn't about controlling the availability of the round so much as the consistency of products on the marketplace. Once Grendel got SAAMI acceptance things were able to stabilize a bit, and he relaxed his grip somewhat.

How about .264 USA...?

Nature Boy said:

AR10 in .260 sounds perfect.

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In doing some research on the above mentioned calibers, last night I finally made the decided that I'm going to go with the 260 Remington ... mostly because the parent case is the 308 and to load for it you simply neck down the 308 case ... I have thousands of once fired brass 308 cases, and couple thousand are LC Match that I've had since the 90's

The 6mm, 6.5 Creedmore 6.5 Grendel vs 6.8 SPC can handle the heavier (and longer) bullets but I'm thinking the more common 120 & 140 grain bullets will be fine for my needs ... which is mostly just punching coyotes and paper.

barnbwt said:

There was a bolt thrust issue if you load it to the full 50-60ksi the brass is rated for (and which most smaller-case cartridges in the AR operate at), but a combination of 9130 bolts and backing off on the pressures to around 40ksi or so seems to have alleviated the issue from what I've been able to determine from my research.

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Sure - by my math the bolt thrust is the same a 5.56 at 42.5K PSI. So to make up for the missing material, 40K is reasonable.

Problem is, 6.5 Grendel under-performs both 5.56 and 6x45 once downloaded. So what's the point?

My 6.8 has been a fantastic rifle

It shoots the Hornady SST 120g and maintains 1000ft lbs at 275 yards

I would probably still take a shot at 300 yards with this bullet


It has dropped some very big Texas pigs.......

Sure - by my math the bolt thrust is the same a 5.56 at 42.5K PSI. So to make up for the missing material, 40K is reasonable.

Problem is, 6.5 Grendel under-performs both 5.56 and 6x45 once downloaded. So what's the point?

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Allegedly, this is a bit of a sweet spot for accuracy when using the standard 123gr VLD bullet from a 1:9 barrel, for one. For two, you still get to use longer projectiles with higher BCs than those other two cartridges if I am not mistaken, while still tossing more mass down range, so wind resistance & momentum is superior. Lastly, if using long barrels that make most efficient use of Grendel's larger powder volume, the reduced peak pressure does not drop velocities all that much (I'm thinking it was at most like 100fps). That pressure peak ultimately forms a fairly small portion of the overall pressure curve, so dropping it down & using a long barrel with slower powder limits the trade-off. Obviously this does hurt the competitiveness of the AR15 Grendel vs. more short-barrel friendly rounds like 6.8spc, but Grendel shooters seem to typically be more accuracy-oriented vs. tactically-oriented, so it is less of an issue (unless you're claiming it to be a 'universal' solution, like 6.8 purports to be with its stubby, lower BC bullets )

Again though, from what I have researched (not quite done with my build to where I can start experimenting on my own) the step back from magnum pressures really doesn't reduce the effectiveness of the round all that much, but makes it far more amenable to the popular AR platform. VEPR and bolt-gun owners can handload it to higher levels if they really care to, and I suppose some do. It just hasn't been shown to reap rewards significant enough to justify making the round too powerful for the AR15. As this thread has shown, the 6.5-in-an-AR niche is really crowded right now, so to say one 'outperforms' another --any other-- is kind of hyperbole. We're talking less than 100fps second differences, and usually less than 20gr deviations, chambering to chambering.

The brass tacks of what type of bullets you want a good selection in (for me, high BC's suggest 6.5 is a good place to start, vs. 6.8), the barrels you want a good selection in (6.8 is by far the cheapest for blanks at this time, but I found a 50$ chambered barrel blank), and available components (quality Lapua brass for Grendel & Hornady dies wasn't significantly different from the others)

And last but most important; I have two RPD kits and Grendel fits in RPD links like it was made for them. At 800yds, you have similar drop & higher energy (with higher sectional density) than 308, from a platform at least 10lb lighter than an M240. The 7.62x39 case head size may be a pointless commonality in the AR15 (it is), but there are a whole lot of cool guns out there designed for x39 that can be readily adapted to a FAR more effective variation of that cartridge. Many can even take advantage of the accuracy benefits, if properly prepared. A VZ58 in Grendel would be a platform lighter & smaller than an AK or most ARs, that shoots (not hits or recoils) like a 308. A VZ52 would be capable of feeding far longer/heavier than standard bullets from its 7.62x45 magazines. I am personally most excited for the Kel Tec RDB in Grendel that's been floated, since it promises to be light, compact, sturdy, simple, clean, accurate, controllable, ergonomic, inexpensive among its peers, and highly effective for a huge range of possible roles in this chambering.

TCB

Serious question as I've been following this thread while deciding what to build on a 308 receiver I recently bought ... I'm looking for something with less recoil than the 308 but legal for hunting and further reaching with more energy than the .223/5.56

If you are only shooting 120 grain bullets why did you choose the 6.8 over the 260 Rem? They both use the same diameter projectiles, Is there something more desirable about the 6.8 ... Or un desirable about the 260?
As I mentioned above, I've pretty. Much decided on the 260 as components are easily obtainable.

Part of my hesitation about "newish" cartridges stems from the fact that just because they are SAAMI acceptance doesn't guarantee they will stick around ... I had a 45 gap for a while and it would have me paying outrageous prices if I wasn't a reloader, I really thought as popular as Glocks are ... and the popularity of the 45 it would be a winner, but no ... I was skeptical/wrong about the 40 S&W too, My thoughts were "what's the point?" I have never heard of anyone out running the 45 acp or 45 Colt.

I built a 6.8SPC for most of the reasons, but 800m and combat are mutually exclusive. Most actual combat takes place out to 125m - beyond that the enemy is using cover and concealment to maximize the extremely short window any soldier practices to reduce open exposure.

The concept of being able to pick off the enemy at 800m standing around in open view is an extreme fantasy. Sure highly trained snipers do that - but once the shot is taken counterfire is the normal consequence and the "operator" is now their downrange target. Which is why they use extremes of concealment and movement.

The AR is more than reliable enough, given competent choice of components, assembly, and quality ammo.

If more power is needed, then another upper in .375 SOCOM could be part of the package. If more volume of fire is desired, then a binary trigger and a 5.56 upper would do.

Ammo costs are a significant part of the package, one reason why I built the next gun in 5.56 as I can buy THREE times as much ammo for the same cash. That is an important factor - it increases practice and reduces the cost of it by a factor of three, too.

Given the requirements in the OP, there's a lack of reality and trimming it down to what the range and target to be encountered 85% of the time will help define which direction to go. That defines the ballistic application, narrows which cartridge will be used, what size receiver and barrel length, the gas action, forend, trigger, optics, and then whatever is left in order of priority. Choose the cartridge for the job, first, not what action length is cool. Things get more exclusive as the range and target are defined which settles most of the questions and makes for a better gun.

but 800m and combat are mutually exclusive

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RPD

Given the requirements in the OP, there's a lack of reality and trimming it down to what the range and target to be encountered 85% of the time will help define which direction to go

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Come now, not even the military can do that

TCB

If you are only shooting 120 grain bullets why did you choose the 6.8 over the 260 Rem? They both use the same diameter projectiles, Is there something more desirable about the 6.8 ... Or un desirable about the 260?
As I mentioned above, I've pretty. Much decided on the 260 as components are easily obtainable.

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Just FYI, the 6.8 SPC and .260 Rem do not use the same diameter projectiles (6.8 ~ .277", .260 ~ .264"). The 6.8 SPC is desirable to some because it is available in AR-15 sized rifles, while the larger .260 Rem must be chambered in larger, heavier AR-10 sized rifles. If you already have AR-10 size receivers, then your decision would be between .260 Rem, and 6.5 Creedmoor, both of which are 6.5 mm adaptations of the .308 case (technically the .30 TC in the case of the 6.5 CM). One of the advantages of the 6.5 CM for this purpose is that it was actually optimized for use in semi-auto rifles. The shoulder is pushed back and chamber is designed so that you can load close to the lands without exceeding mag length; my 6.5 cm loads are .010 off the lands, have an oal of 2.76" and feed fine through Pmags. The advantage of the .260 Rem would be that it is easier to form cases from .308 brass if you can't find .260 brass. I've been able to build up a decent stock of 6.5 CM brass just by buying when I see it in stock, but it is sold out some of the time.

For your specific purpose out of the 3 listed I'd get the .308 simply because it has more ammunition availability. A rifle isn't much good if you can't find ammo and it sounds like you'll mostly be using it to hunt with, target shooting and perhaps as a defense guns in case our cities burst into flame, aliens invade or Russian paratroopers fall from the sky...'Wolverines'.

Sorry, had to get that out.

I owned a 6.8 SPC (Stag Arms with a 20" barrel) and used it to take a few deer and (literally) a ton of hogs. It worked great and I really liked it for what it was (a 6mm and then some auto loading cartridge midway between the .223 and .308 that put game down well with the recoil near a .223 but that knocked game down well like a .308) but eventually I got sick of tracking down ammo for an okay price and sold it to a buddy. Lot of hog and deer hunters are into the 6.8 SPC.

The 6.5 Grendel is a great cartridge and it has some real long range potential, but with ammo it's the same deal as the 6.8, kind of a pain to find. It's a real flat shooting and an accurate cartridge though.

For this one though there is a small but vocal group that has some axe to grind against this caliber who are always selling horror stories of broken bolts and whatnot. However their stories always happened to someone else and are short on pictures, video and details. Kind of funny that everyone I know who owns a rifle in this cartridge has never had any of these problems. The main problem you'll have with the 6.5 Grendel is tracking down ammo or (if you're a hand loader) components. Mostly the long range crowd is into this caliber.

If you get into either the 6.8 or the 6.5 I'd figure on hand loading right off the bat unless you're lifestyles of the rich and famous type of rich.

Then you have the .308. With the .308 Win you'll have plenty of rifle choices. Ammo is readily available although it's not as cheap as it was in the 80's and 90's. I've always gone with the FAL (both DSA and Imbel), the Springfield M1A, the H&K 91 / PTR-91 and avoided the AR's in .308. With those three main types of rifles (FAL - M1A - H&K 91 or an exact clone of good quality) there are a ton of parts and mags and they have a good history of working well.

With the AR-10 (I'm using the term AR-10 as a stand in term for any AR in .308 even though most of these rifles have nothing to do with Armalite) you have 20 different manufacturers who all put out a different design using different mags and parts.

DPMS .308's have somewhat of a mixed reputation among shooters. That's because some are using them as hunting rifles and they might see a few boxes of ammo a year max and for those shooters they're having a positive experience with these rifles. The shooters who are trying to get some hard use out of them are mostly disappointed. Unless I saved up my duckets for something like an LMT MWS I'd recommend that you pass on the AR-10 idea in general and the DPMS idea specifically if it's going to be rode hard and put up wet at all.

So I'd get a .308 and I'd probably recommend an FAL by DSA or a PTR-91 (copy of an H&K 91). Either of those will fill your needs with hunting, high powered plinking of for defense if things take a turn for the worse.

I have a PTR-91 as my knock around hog gun.

I have no dog in the caliber controversy and would only offer the following: It is quite easy to get a 308 to 2900 plus velocities and any recoil problems are easily handled with a good pad and muzzle brake. If you want to nitpick, the smaller calibers have a slight advantage in bc numbers and use a little less powder. I hunt with a factory 5lb rifle(kimber mt.ascent) and 150g ttsx handloads at 2950 fps. That load is with rl15 and 1 g under max. It kills elk just fine at 300yds and beyond. For a bench gun it is too light. I used to hunt with magnums so the 308 seems small to me so maybe I just need to take the next step. I have the caliber itch like everyone else but sometimes when you step back it is just that, an itch, really does not amount to much. Good luck with your decision.

The other consideration is that can you even see 800 yards for most shots against hogs in the OP's area? What about 400? I've seen one shooter make a second round hit on a deer at a pretty solid 400 yards in my life, and that was a very rare occasion by a pretty remarkable shooter. I used to have the chance to shoot on a fairly regular basis at a Black Powder Silhouette range - steel chickens at 200 yards, pigs at 300, turkeys at 400, and I think rams at 500. I was a member of the club and I could shoot at them any time I was willing to walk out and set them up as long as there was no match that weekend. The pigs weren't too hard to hit with an open-sighted SKS and a little luck... but that was on a sunny day with no adrenaline and plenty of time. Even then, sometimes the clouds would be wrong and you'd have a hard time making the pig out against the berm.

Long story short, even if you do have a rifle that will shoot to 400 or 800 yards, when you're hunting, maybe you shouldn't try to shoot that far.

For overall shootability, the Grendel or 6.8 are the better choices for the parameters given in the OP. The 6.8 has a much wider availability of parts, model choices, and ammo. .308 is an outstanding caliber, but has a lot more recoil which may not be advantageous for SD situations.

6.8 or 300 BLK could actually meet those requirements fairly well. 308 will be pretty big and heavy for up close self defense.

I would go for a longer barrel than 16 inch if you are going 6.5

That round does better with a longer barrel, and the extra speed

My personal max range at hunting is 300 yards. It has to be exactly perfect shot at that range though.

I feel that if I had a bad shot,

(yeah.... in the woods, WITHOUT A NICE, COMFORTABLE BENCH REST....Annie Oakley has some bad shots)

The wounded animal can get some major distance from the spot that you shot them at, by the time you got there. I also dont like the fact that I cant see what is BEHIND the critter as well at that distance.

I see so many people that are bench rest commandos, and think the nice group that they get at 100 yards at the nice range, will somehow be perfect at 300 plus yards out in the field.
(Not saying you are one of them)

Good luck on your choice......... I went through this same choice, and looked at EVERYTHING and for many reasons.... went 6.8

It has been a great choice so far........

I am still trying to find a reason to buy a 308 ...... just always seem to find a reason to buy something else....... (Or my wife chooses )

Take care, and may God bless you.... be SAFE

Since you decided on the Grendel, if you don't reload, Hornady SST 123 gr. ammo does very well on hogs and deer. Many folks using the thinner skinner AMAX 123 gr. for deer. I can tell you that the SST is not pelt friendly on coyotes and bobcats.

Federal has come out with a line of Grendel ammo, just one offering last I checked but they are supposed to come out with more.

Some people like the PPU ammo. I have not seen it.

Wolf Gold (brass case) works okay. It is inexpensive and I keep some on hand for getting new scopes on paper before attempting to zero with more expensive hunting ammo. Some folks swear by it, but I don't fine it is a reliable cycler in my primary hunting rifle.

Also see... http://ammoseek.com/ammo/6.5mm-grendel

www.precisionfirearms.com has a variety of specialty ammo for the Grendel. They load a lot of bullet types and apparently are somewhat anal-retentive about their procedures and charge accordingly. I purchased some pricey Berger VLD-Hunting ammo from them and have NO complaints about the quality of the loading. They can be slow to fill orders, but their stuff is very good good.

If you do reload, contact me in a month or two about some brass. I can maybe help you out.

Longer barrel makes better use of Grendel's qualities; for a 16" or shorter, I'd definitely say SPC has the edge (plus it'll be cheaper). Any of these AR-length ~6mm cartridges will be adequate out to 400yds (which is basically mid way through the effective ballistic range, where all the different rounds truly are just about identical, since wind & drop & drag haven't had nearly as much impact on things)

TCB

Huntolive, I have the Incursion. It is very light. You are going to lose 150 fps or so with it for 123 gr. ammo. YMMV as each barrel is different. I got the Incursion for my daughter to carry. I am a fan of the additional velocity of longer barrels.

With the Incursion and a 123 gr. factory Hornady ammo, you should still be over 1900 fps and 1000 lbs of energy at 300 yards.

Your Mileage, May Vary. Mileage will vary, in this case.

TCB

Well, I've got a Grendel that has not given me trouble. But for your requirements I'd also throw the 300 Blackout in the mix. I regularly take deer out between 125-200 yards with 110-125gr premium bullets (Barnes or Nosler), uses the same 30 round mags with the same round count, is a reloaders dream, and is dang quiet with a 16" barrel and an A2 hider. I've heard it argued this is a cartridge looking for a solution, but where you can't shoot deer with a 223, I find this is a mighty fine purpose. My friend and I shoot deer year round and this round has quickly become a favorite.