Are we barking up the wrong tree with the 6.5 Grendel and 6.8 SPC


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Grump
May 15, 2006, 09:10 PM
Had one of those dangerous brain flashes.

Much of the talk on both of these rounds is how they can "out-perform" even the mighty 7.62 NATO beyond 500 meters, usually in wind drift and about equalling trajectory...at least when using the heavier bullets.

But I have a couple of concerns here:

1. The price to get that is usually a pretty low velocity around 2550 or so, which really doesn't give us the really nice and flat trajectory of the 5.56 M193 from 0-300 meters, where a difference of 1 MOA on those half-exposed helmets can really make a difference.

2. The load being "beaten" is the lowly M80 ball round, which is a little light for downrange barrier penetration anyway.

So, won't we get some better balance of the military benefits if we stick with lighter, slicker bullets of about 95-105 grains, keep the speed up, and worry about BOTH wind drift and trajectory?

Barrier penetration may be better addressed with the AP rounds anyway. My sources indicate that the .30-06 AP round was issued like candy in WWII, maybe even in greater numbers than M2 Ball. It was also accurate enough that many military target teams my pappy met in the '50s and '60s liked it more for practice than anything other than Match ammo.

I'm also uncomfortable with proposing an infantry ammo "solution" that uses bullets almost as heavy as M2 Ball or M80 Ball, as our consumption of strategic metals in wartime is a factor that *can* win or lose the whole war. Using a 123-gr bullet just seems to be a step too far in the other direction.

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R.W.Dale
May 15, 2006, 09:29 PM
I think that you're barking up the wrong tree by actually believing the hype that either of these rounds is being looked at by the military. These are purely commercial affairs no diffrent than 25-06 or 338wm. They are primarly being foisted apoun us buy the gun media in order to justify more advertising dollars.

browningguy
May 15, 2006, 10:19 PM
While I'll agree that neither one will likely ever make it into the military I'll have to disagree with the foisted upon us bit.

I don't have much time for the 6.8 SPC admittedly, but the 6.5 Grendel actually makes pretty good sense. Excellent ballistics and a much better round for hunting deer size critters than the .223. In some states they tell me you can't even hunt deer with a .223. So if you want to try your AR then something like this makes sense to me. You could argue the same for the 6.8, but I just don't like it.

I don't have either one by the way, in order to maintain my local image for being an ornery old cuss (that's the polite version) I had Teppu Jutsu build me a 6x45 upper for hunting and target work.

http://img.photobucket.com/albums/v11/jcm9371/Rifles/6x45receiver.jpg

Redhat
May 15, 2006, 10:23 PM
What are the velocities of the M855, 6.5G, and M80 compared at 0,100,200,300,400,500... yds?

Does the 6.5 start out slower but maintain speed down range due to a better BC?

Preacherman
May 15, 2006, 10:58 PM
I don't think that either round is "barking up the wrong tree" - they're just different answers to the same tactical problem. Let's look at the problem, rather than one particular solution, and then consider the answers.

The problem is that during WW2 and Korea, studies showed that the vast majority of effective shots by infantrymen were at relatively short ranges (less than 200 yards in something like 90% of cases, IIRC). Furthermore, many infantrymen, under the stress of combat, couldn't reliably hit their targets at even close range. Longer-range shots were the province of trained marksmen and those few infantrymen who could keep their cool under fire - a very small percentage.

This meant that the standard .30-caliber battle rifle round (and its foreign equivalents such as 7.92x57mm. Mauser, 6.5mm. Swedish, .303 British, etc.) were over-powered for the "average" shooter, being accurate out to several hundred yards, in rifles designed and equipped with sights for shots out to 1,000 yards or more. Also, these rounds were relatively heavy, limiting the amount of ammo a soldier could carry. The development of the 7.62x51mm. NATO round as a "compact" .30-caliber helped a little, but not much.

So, armies looked for ways to solve the problem. One solution was the German "short Mauser" round - a full-caliber 7.92mm. bullet in a shortened case, with lower velocity, recoil, etc. This was extraordinarly effective, particularly in the StG44 assault rifle. The Russians followed suit with their 7.62x39mm. round for the SKS and AK rifles. These rounds were much lower in recoil than the full-house stuff, and more controllable (particularly in full-auto fire), but still almost as heavy as the bigger rounds, so that not much more ammo could be carried.

A number of countries experimented with much smaller rounds overall, including Britain, the Netherlands, and the USA. The US 5.56x45mm. round eventually came to dominate the scene. It was so small a round as to be illegal for all but varmint hunting in many areas, but could still inflict a significant wound on a human being - particularly in full-auto fire, where multiple hits magnified the effect. Its extremely light weight also meant that the individual soldier could carry more than twice the ammo of the heavier .30-caliber rounds. However, long-range effectiveness was marginal - not a problem to the designers, or the Army, both of whom wanted a round that would be effective at typical combat distances.

Today, the 5.56mm. is derided as being ineffective against cover, in comparison to the .30-caliber rounds, which would turn a lot of cover into nothing more than concealment. It's also criticised for being less than effective as a "stopper" in its current military ball round (SS109). This is a valid criticism - the SS109 was specifically developed to give greater penetration at long range, being designed to penetrate a NATO-standard Kevlar helmet at 600 yards. Obviously, if built for deep penetration, its tumbling and fragmentation effect (pretty good in the earlier 55gr. rounds) has had to take second place. However, the overall advantages of the 5.56mm. - lower recoil, greater controllability (particularly in full-auto fire), greater ammo carrying capacity, etc. - still outweigh these disadvantages, and have ensured its survival.

The 6.5mm. and 6.8mm. rounds are an attempt to find a "happy medium" - a round that will provide better terminal performance in flesh than 5.56mm., penetrate cover better, be accurate and effective at longer ranges, and yet be light enough to permit a significantly higher ammo load than the old .30-caliber rounds. They're trying to be "all things to all men". The approach is admirable, as is the intent, but they have to overcome a supply system filled with perfectly usable rifles, accessories and ammo for the current 5.56mm. systems. Unless the new rounds offer a significant advantage over what they're trying to replace - significant in every way, including cost to implement! - they won't displace the existing round.

This happened before, with the Garand. It was designed to use a .276-caliber round (6.5 or 6.8, anybody?). MacArthur rejected this, insisting that it be designed to use the .30-'06 round already in use in the Army, so as not to waste the millions of rounds of ammo already in stock. I think the Garand would have been a much better rifle with the .276 cartridge, but the inertia of the system overcame its technical advantages.

beerslurpy
May 15, 2006, 11:25 PM
The 6.8 SPC doesnt really bring anything new to the table. It is basically a straight compromise between 5.56x45 accuracy and 7.62x39 stopping power. But like the these rounds, it suffers from poor BC because there is relatively little cartridge length compared to a full power cartridge.

6.5 Grendel puts the ballistics of a 7mm rem mag into what is basically an upgraded version of 7.62x39. 6.5 Grendel strikes essentially the same muzzle velocity vs knockdown power compromise as 6.8 SPC, but it doesnt bleed off energy like all the other intermediate cartridges so it offers that much more in terms of effective range.

I honestly do think that the marines are at least considering the 6.5 grendel. They love long distance shooting and the fact that they are looking at drum-fed instead of belt fed LMGs is an encouraging sign.

raz-0
May 16, 2006, 01:56 AM
Handle an ar-10 and an ar-15 other than shooting off a bench or prone. Then you will know why 6.8 and 6.5 exist. The shorter, lighter gun just handles a HECK of a lot better for a larger range of people sizes and shapes. It is very modular, and there are lots of aftermarket bits for it. Much like the super short magnum cartridges, the same thinking is makign it to the AR platform.

It's not some kind of scheme or anything, it's jsut making cool new toys for the most part.

6.8 might actually be viable as a military cartridge, but the 6.5 I view as more of a civilian cartridge designed to make the most of your AR platform. I.e. long range shooting and actual hunting without duplicating all your lower work on an ar-10 or clone.

Crosshair
May 16, 2006, 03:03 AM
Actualy the 6.5 Swede was a very good round that never saw much combat use. True the weight of ammo is not much less than 7.62x51, but the round had low recoil and excellent terminal ballistics, even in FMJ. Of all rounds available at the time I think the 6.5 Swede was the best compromise. Put it in an autoloader and you would have a good select fire weapon. Yes the recoil is a little much for full auto, (Less than 308 though.) but since most trained troops only use semi-auto anyway, it is not that much of an issue.

Preacherman
May 16, 2006, 03:53 AM
6.5 Grendel puts the ballistics of a 7mm rem mag into what is basically an upgraded version of 7.62x39.

With respect, I have to disagree with this comment.

From the Alexander Arms Web site ( http://www.alexanderarms.com/grendel_ballistics.pdf ), we see that a 123gr. bullet has a MV of 2600 fps, dropping to 2441 fps at 100 yards. Its muzzle energy is 1847 ft/lbs., dropping to 1627 ft/lbs. at 100 yards.

From Remington's ballistics info ( http://www.remington.com/products/ammunition/ballistics/results/default.aspx?type=centerfire&cal=20 ), we see that a 140gr. 7mm. Magnum bullet has a MV of 3175 fps, dropping to 2923 fps at 100 yards. Its muzzle energy is 3133 ft/lbs., dropping to 2655 ft/lbs. at 100 yards.

So, the Grendel is almost 25% down on the 7mm. Magnum's muzzle velocity, and almost 70% down on muzzle energy.

ryoushi
May 16, 2006, 04:05 AM
The 6.8 SPC succeeds at what it was intended to do. Provide a much harder hitting bullet than the .223 while maintainig approx. the same trajectory and still function reliably on the AR15 platform without having to completely revamp the weapon. A 25 rd 6.8 magazine is the same size as a 30 round .223 magazine.

The 6.5 Grendel smokes the 6.8 at ranges beyond 300 yds. and seems to work well in AR15s too. I haven't seen the Grendel Magazines but would assume that all things being equal, capicity is a bit lower than the 6.8 as the Grendel cases are fatter than the 6.8.

Of course there are many rounds that out perform these two but they are a no go in an M4.

SIGarmed
May 16, 2006, 09:26 AM
Much of the talk on both of these rounds is how they can "out-perform" even the mighty 7.62 NATO beyond 500 meters, usually in wind drift and about equalling trajectory...at least when using the heavier bullets.

It's not "they" it's the 6.5 Grendel that can keep being supersonic beyond 1000m.

beerslurpy
May 16, 2006, 10:47 AM
When I said ballistics of the 7mm rem, I should have specified I meant bullet design, not the muzzle velocity or bullet weights. Look at the BC of the bullets. All the intermediate cartridges are stuck around .1-.3. Grendel goes from .4 to .7 almost. That is 7mm rem territory and that is what gives it the long reach.

7.62x39 would probably be a easy 500 yard cartridge if it didnt have such poor BC. It is amazing how quick and flat it starts out and then how quickly it loses steam and falls like a rock. Shooting 6.5 grendel from a 14 inch barrel almost exactly recreates the muzzle velocity and weight of the 7.62x39 but it doesnt fall on its face after 300 yards. It drops, but the drop amounts are relatively small. An MOA or two every 100 yards, even after 400 yards.

ryoushi
May 16, 2006, 12:55 PM
Well there are certainly a number of 7.62MM progectiles with a very good BC it's just the 7.62 X 39 doesn't have enough case capacity to generate the velocity needed to give you the type of performance I think your talking about.

There are some heavier 6.5 bullets available (http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&submit=1&stock_num=1742&bullettype=0) with outstanding BCs but I don't think the Grendel can throw those things at the needed velocity. 260 Remington will but try stuffing that into an M4.

The beauty of the 6.8 SPC is that it works so well for it's intended purpose, maximizing a 16" M4's stopping power at typical combat ranges while still keeping recoil down.

ArmandTanzarian
May 16, 2006, 02:27 PM
Your point is well-taken and the answer is yes, a .257 or possibly a 6mm with a 100-115 gr bullet is going to be the ideal compromise between flat trajectory, terminal performance at all ranges, penetration at long ranges, etc., in my view, *if* we're stuck with one round for the main battle rifle and GPMGs, AND *if* we're stuck with the 14" rifle. Think .250-3000 Savage Lite - something like a .257-6mmBR, or .257-6x45mm. The 6.5 grendel would be the third best choice. 6.8, bah...not enough energy retention in the light bullets, and not enough speed for a good point & click PBR with heavy bullets. Far too much like 7.62x39mm to be any real innovation.

Grump
May 16, 2006, 06:23 PM
ArmandTanzarian:

I happen to believe that either a beefed-up 6.8 SPC (maybe...) or just a 6.5 Grendel could give us the unfulfilled promise of the M14 as it was envisioned in 1950-whatever and delivered in 1957--one round for almost everything ground troops use except the pistol.

Seems most of the criticisms from the "M14 was a failure" group, AND from the ".223 is just a varmint gun" group, could be addressed with that round, while re-gaining almost all of what was lost by going away from the 7.62 NATO as far as wind drift, hit probability, and impact energy. It's admittedly lighter than the M80 ball, could perhaps equal M118 match for long-range hits, and certainly outdo any of the current 5.56mm variants in use.

Extreme penetration needs would be addressed with AP ammo, Barrett .50s, and your crew-served weapons. Lose the supply chain problems of SAW ammo and GPMG ammo.

So, I think that the overall benefits (including eliminating the copper-hog, powder-hog, shipping costs problems of having ANY 7.62NATO ammo in the system) of switching to a mid-caliber round makes it a *good thing* for our troops to be "stuck with" one round for rifles through GPMGs.

Rifle, pistol, .50s, three ammos is all we should need.

Then there's my wild idea of extending the Grendel's shoulder to allow a bit more powder--loaded long for a new weapon, DMR system, and sniper system, and the shorter-loaded lighter bullet rounds staying at AR magazine-length.

Seems like we're sacrificing our ideal of an intermediate rifle round on the altar of AR system magazine well depth.:neener:

You could even design the long-load magazine guns with a step on the forward end to accomodate the longer OALs of the specialty ammo, while allowing the same specialty rifle to use the modified AR mags used by all the rest of the grunts. After all, don't we single-load the Sierra 77-gr OTM load in the ARs right now? Pardon me if I'm wrong on this one--I quit shooting highpower competitively in the days of the Sierra 69-gr Matchking...and never believed in shooting "service rifles" with ammo that won't go in the magazine, no matter what.

Don't Tread On Me
May 16, 2006, 06:39 PM
You know, the AR platform, and the 5.56 aren't so bad.


The best bet is to outfit our soldiers with a new round. A cost-effective, non-match grade, 75gr FMJBT with a hollow cavity in the nose and cannelure. Just design and manufacture a cheap bullet that will still yaw and fragment like crazy.


That will extend the fragmentation range out to 285 yards. Nearly 50% more range. At ANY distance, it will outperform the current military 5.56 loads in terminal performance.


That should solve the already blown out of proportion complaints and platform problems that fuel AR/223 hate on the internet. Naa it won't. What am I thinking? Unless the U.S. military adopts either the M14/AK for a rifle, and a .308 or .270 caliber cartridge, people won't be "happy"...

ArmandTanzarian
May 16, 2006, 08:13 PM
Seems like we're sacrificing our ideal of an intermediate rifle round on the altar of AR system magazine well depth

Grump, You're right and we shouldn't. On the drawing board at least, for the "1 rifle/saw/gpmg-round-supply chain", the limiting factor should not be "what can we fit in an AR?" ... It should be instead "What is the max round that is highly controllable in full auto and still beats the 5.56 at short ranges and matches or beats the 7.62 at long ranges?" and to a lesser extent, "what is still much much lighter & smaller for grunts to tote around large quantities than 7.62 nato?" So a 6.5 grendel +5% or +10% would be pretty darned nice...now just need the appropriations for completely new rifles & mags! :)

beerslurpy
May 16, 2006, 09:49 PM
The problem is that any cartridge that doesnt kneel before the AR mag size altar is going to lose out in procurement to any cartridge that does. The 6.5 grendel addresses all the complaints people have about current military issue cartridges, at least for use against humans. I could see very high BC 30 caliber rounds having some selling points, but to push them at 3000 fps would generate a lot more recoil than on a 6.5mm weapon with equivalent BCs.

Zundfolge
May 17, 2006, 12:19 AM
The best bet is to outfit our soldiers with a new round. A cost-effective, non-match grade, 75gr FMJBT with a hollow cavity in the nose and cannelure.

My thoughts exactly ... except for the fact that such a round would probably violate "international law".

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