Da..it, Don't shortchange me! 6.5 Grendel vs. 6.8 SPC


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autobahndriver
July 19, 2004, 10:55 AM
I don't want another compromise round (6.8 SPC)


The 6.8 SPC is a "limiting" cartridge in that it's effectiveness is less at longer range. :(
I don't want another cartridge that limits me in some way.:mad:

The 6.5 Grendel can be a good round for some of the long ranges we are now seeing in Afghanistan. :)
Why go to a 6.8 SPC - good for short range - and then find ourselves wanting a good long range shooter as well as short range terminal performer?:confused:

Energy delivered are similar between the 6.8 SPC and 6.5 Grendel at short range and they are similar sized bullets.
At longer range 300+ meters, the Grendel significantly outperforms.

Remember that our situations will continually change and we will find ourselves wanting.

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autobahndriver
July 19, 2004, 11:13 AM
Ballistics Comparison:

6.8 SPC / 6.5 Grendel
Sierra 115 gr / 123 Scenar Lapua
.340 BC / .542 BC

2422 / 2427 fps at 100m
1498 / 1609 ftlb at 100m
+6.06 / +5.76 in drop at 100m
1.20 / .90 in drift at 100m (10mph)

1916 / 2102 300m Velocity
938 / 1206 300m Energy
0 / 0 300m Drop
12.05 / 7.49 300m Drift

500meters:
1488 / 1803 Velocity
565 / 888 Energy
-52.41 / -43.73 Drop
37.8 / 22.41 Drift

….and the 6.5 Grendel just gets better compared to the 6.8 SPC as range increases.
At 1000m the Grendel still has 1222 fps Velocity and almost twice the energy as the 6.8.

Both the 6.8 SPC and 6.5 Grendel weigh 11.5 lbs per 300 rounds.
The 6.8 SPC and 6.5 Grendel have similar recoil (slightly more than a 5.56)
Both the 6.8 SPC and 6.5 Grendel can be used with existing AR15 lower assemblies.

The 6.5 Grendel is better on all accounts – why is there any argument???

ChiefPilot
July 19, 2004, 01:06 PM
I don't want another compromise round (6.8 SPC)

Then use 7.62x51. It's got more short- and long-range energy than eithe the 6.5 or the 6.8, it's less expensive than either, and it's readily available. AR-10 type rifles are readily available as well, as are a number of bolt, pump, and even lever action rifles in the caliber. Problem Solved. :)

I just don't understand the hoopla about the 6.5/6.8 rounds. If you want more than 5.56 has to offer, just get what you want - a 7.62.

sumpnz
July 19, 2004, 02:09 PM
I just don't understand the hoopla about the 6.5/6.8 rounds. If you want more than 5.56 has to offer, just get what you want - a 7.62. I believe the hoopla is that the 6.5 gives you almost everything the 7.62x51 does, but with less recoil and less weight. Also, the 6.5 with the 144 grain bullets, actually outperformes the 7.62 beyond, I think, 400 yards thanks to it's really high BC.

autobahndriver, do a search here on the 6.5 Grendel and you'll find all the info yuo ever wanted, and about every opinion possible expressed on the cartridge.

Grump
July 19, 2004, 02:16 PM
Well, 7.62x51 doesn't make sense militarily. The Grendel can give you at least equal wind drift, and even better, than M80 ball at extended ranges, with very little decrease in terminal energy and virtually the same trajectory.

And M80 ball does that while using MORE powder, MORE brass, copper and lead, LARGER primers, and MORE shooter fatigue. Go to the better 7.62x51 loads like M852 and M118 LR and all those disadvantages become slightly greater, and in enough quantity to make a difference for strategic considerations (more shots per pound of metals ore, greater shipping costs per shot, and more weight on the Grunt for the same combat load of XXX rounds).

The Grendel can make the promise of the M14 doitall compromise rifle actually attainable, with better downrange performance.

What I want to know is whether the reported problems of "accuracy going to pot at pressures bringing the desired velocities" problem of the 6.8 have also cropped up for the Grendel. Anyone?? Anyone?? Bueller??

Sam Adams
July 19, 2004, 02:28 PM
A great website related to the 6.5 Grendel is http://www.65grendel.com/

Personally, I prefer the 6.5 Grendel vs. the 6.8 SPC based on ballistics. The biggest thing going for the Grendel is its BC - this is pure mathematics with which the SPC proponents can't argue. It is simply a better bullet, and the round itself has been optimized from a very accurate benchrest round so as to operate in the M16/AR15 family with minimal, if any, problems. If I could afford it, I'd have already bought either an upper or a whole rifle, together with reloading gear, brass and bullets. I also look forward to this round being developed for a boltie, as it is seriously accurate.

However, the odds of either round being picked as a replacement for the 5.56 mm are small. The latter is considered "good enough" by those in logistics who aren't in combat, plus there is just a lot of inertia in any large organization (esp. government). I'd love to see either round picked, as both are far superior to the 5.56mm (the only reason for this round to be good is very high velocities, which aren't attained in the short-barreled rifles being handed out lately), but of the 2, the Grendel is better. JMHO.

ChiefPilot
July 19, 2004, 02:29 PM
Also, the 6.5 with the 144 grain bullets, actually outperformes the 7.62 beyond, I think, 400 yards thanks to it's really high BC.

True, but the 7.62 with 175gr bullets is better still. Check out the ballistics chart (http://www.65grendel.com/graphics/grendelballistics.pdf) for the 6.5 Grendel - the 7.62 still holds the energy advantage at 1000m.

For my own personal use - the amount of brass, power, and lead doesn't matter as I can buy 7.62 for far cheaper than I can 6.5 or 6.8. For the military, I'd just as soon keep them using the 5.56 and instead put the money towards something like this (http://www.jsf.mil) or this (http://www.f22fighter.com).

sumpnz
July 19, 2004, 02:57 PM
The differences in velocity and energy (for the 144 grain 6.5mm and 175 grain 7.62mm) past 600 meters are academic. Given that very few soldiers will take shots even that long I don't think the small differences really matter (it's only 10 ft-lbs difference at 1000 yards - variations from shot to shot can be bigger than that). Besides, I was intending to comapre against the M80 ball rounds (147 grain). I suppose it would be more appropriate to comapre that round to the 123 grain load for the 6.5. In that case, by 200 meters the 6.5 is going faster than the 7.62, and somewhere between 500 and 600 meters the 6.5 takes over in terms of energy. At 600 meters the 6.5 has a 6" and 10" advantage in drop and drift respectively.

As far as cost goes, were the military to adopt the 6.5 Grendel it would drop in cost very quickly to about that of what 7.62 NATO currently costs. Right now it does not have the economy of scale working to its advantage. For my own personal use - the amount of brass, power, and lead doesn't matter as I can buy 7.62 for far cheaper than I can 6.5 or 6.8. Yes, but we are mostly talking about the military use of the round. For them, weight is a very high priority. It was one of the big reasons they went from the .30-06 to the 5.56mm in the first place for general infantry use.

JShirley
July 19, 2004, 07:48 PM
Hooah! Carrying stuff sucks. Lightweight ammo good. John smash!

Preacherman
July 19, 2004, 08:34 PM
Don't forget that a very, very important factor in the design process for the 6.8mm. round was that it had to be able to fit as many rounds as possible into a standard M16/AR-15 magazine. Thus, the cartridge is narrower than the 6.5 Grendel, and more of the former can be fitted into a standard M16 magazine than the latter.

Makes sense, from a military point of view, no?

sumpnz
July 19, 2004, 08:40 PM
Preacherman - Well yes, but if they tooled up for 6.5 Grendel production they could just make slightly larger mags to fit the same number of rounds, and when they modified the existing mags, they could easily restrict those to training use only until they wore out, or sell them unmodified as surplus. So long as the AWB expires, and is not brought back in near term there would be no problem with that.

TODD3465
July 19, 2004, 08:50 PM
As far as I know the 6.8SPC was develped with SOCOM and wide spread military use will probably be non-existant.

However it would probably have a better chance at being adopted as it will be getting more exposure through actual combat use than the 6.5Grendel.

sumpnz
July 19, 2004, 09:23 PM
Well, considering how much better the 6.5 Grendel performed at Blackwater, I would imagine that SOCOM might be at least somewhat interested in field testing of that round too. Certainly if I were in charge of those decisions that would be my approach. Whether or not they actually do so is another matter entirely though.

Personally, if I can ever scratch up the cash to buy an AR-15, and the cash for an upper in either 6.5 or 6.8, I would choose the 6.5. And if I had the cash for two uppers, I'd get one in 6.5 with an 18.5" carbine barrel, and one in 6.5 with a 24" or 28" match barrel. And if I really had too much money to spend on AR conversions, I'd probably go for a 50 Beowulf upper (more to frighten DiFi than anything else), and maybe some other calibers like 22lr (for cheap practice), or 9mm, 40S&W and 10mm (since I like the idea of pistol caliber carbines as companions to a sidearm). But I doubt I'd ever bother with a 6.8SPC upper. I just see much point (for myself) for such a limited round that is matched or beaten by the Grendel with very little lost on the compromises that are made.

TODD3465
July 19, 2004, 10:25 PM
The makers of the 6.5 can blow their horn about Blackwater testing it all they please but the 6.8SPC round is what is being used by the military not the 6.5.

Right now a major ammuntion company (Remington) is starting to crank out the 6.8SPC and they have 3 versions of the ammo that will be available to civilians pretty soon.

Myself I don't have any personal interest in either one. Until the military actually adopts sometrhing new I'll stick to .223 and .308 in my semi-autos.

sumpnz
July 19, 2004, 10:52 PM
(Remington) is starting to crank out the 6.8SPC and they have 3 versions of the ammo that will be available to civilians pretty soon. Yeah, and they're all 115 grains AFIAK. Just a matter of whether they are FMJ, soft point, or whatever.

The big thing that I like about the 6.5 Grendel, regardless of military acceptance, is that it can take 90-144 grain bullets. That makes it much, much more versitle. The 6.8, which is basically a member of the .270 family, can only go up to 115 grains. If I wanted a .270 for hunting, I'd go with a .270 Wincester, which at least allows for bullet weights up to 150 grains (possibly higher, but that's as heavy as factory loads typically go).
The makers of the 6.5 can blow their horn about Blackwater testing it all they please but the 6.8SPC round is what is being used by the military not the 6.5. And, as I mentioned before, I think that's a mistake. When I'm king of the world all such idiocies shall be recitified. Until then, I'll pin my hopes on commercial success of the 6.5 Grendel. And let's face it, the 6.8SPC just will not compete in the market place based on its performance. I don't know what 6.8 uppers are going for, but even if the Grendel uppers were $200 more, I'd still bet on the Grendel winning the war for the wallets of consumers.

autobahndriver
July 20, 2004, 04:53 AM
Preacherman:Don't forget that a very, very important factor in the design process for the 6.8mm. round was that it had to be able to fit as many rounds as possible into a standard M16/AR-15 magazine. Thus, the cartridge is narrower than the 6.5 Grendel, and more of the former can be fitted into a standard M16 magazine than the latter.

The 6.5 Grendel will fit the same amount of rounds in the same magazine as the 6.8 SPC. There is only the thickness of a sheet of paper difference in case diameters!

autobahndriver
July 20, 2004, 04:59 AM
The makers of the 6.5 can blow their horn about Blackwater testing it all they please but the 6.8SPC round is what is being used by the military not the 6.5.

The military will be using the 6.5 Grendel as well. Spec Ops has great latitude in what they choose to use. Example: H&K SOCOM (MK23) was developed by military contract for US Spec Ops use yet various Spec Ops groups still adopted different pistols (Seals - Sig due to being more compact).

Now if we could get a better round adopted for the rest of the military!

I think the major selling point for the military would be one round to replace both the 5.56 and 7.62.

The 6.5 Grendel performs very close to all 7.62 rounds in energy delivered but has better ballistics and lighter cartridge weight.

I plan to get a personal 6.5 Grendel upper.
I am promoting further testing of the 6.5 Grendel currently within the military.
I will promote adopting the 6.5 Grendel within the military if use over the next couple of years does not show any problems.

autobahndriver
July 20, 2004, 05:09 AM
Ballistics of 6.5 Grendel compared to 5.56 and 7.62 NATO:

6.5 Grendel / 5.56 NATO / 7.62 NATO / 7.62 NATO
123 S.Lapua / M262 / M80 / M118LR
.542 BC / 340 BC / .418 BC / .496 BC

2750fps / 2600fps / 2700fps / 2500fps Muzzle Velocity
1293ftlb / 1846ftlb / 2379ftlb / 2429ftlb Muzzle Energy

2102 / 1957 / 2051 / 1971 300m Velocity
1206 / 655 / 1373 / 1509 300m Energy
7.49” / 11.72” / 9.48” / 8.77” 10mph Wind Drift

1803 / 1521 / 1676 / 1661 500m Velocity
888 / 396 / 917 / 1072 500m Energy
-43.73 / -50.18 / -45.73 / -49.81 500m Drop in.
22.41 / 36.76 / 29.03 / 26.44 10mph Drift

1222 / 954 / 1063 / 1113 1000m Velocity
408 / 156 / 368 / 481 1000m Energy
-422.87 / -591.67 / -491.29 / -497.96 1000m Drop
107.83 / 182.73 / 144.55 / 127.31 1000m Drift

300 rounds ammunition weight:
6.5 Grendel w/123 S.Lapua – 11.5 lbs / 300 rnds
5.56 NATO M262 – 9.0 lbs / 300 rnds
7.62 NATO M80 – 13.8 lbs / 300 rnds
7.62 NATO M118LR – 15.0 lbs / 300 rnds
6.8 SPC same weight as 6.5 Grendel

*this is 20" barrel information - shorter barrels give a greater advantage to higher BC bullet and a case closer to short magnum in shape.

ChiefPilot
July 20, 2004, 08:27 AM
Ballistics of 6.5 Grendel compared to 5.56 and 7.62 NATO:

Source? *EVERYTHING* else I've seen acknowledges that a 175gr 7.62x51 load is superior to the 6.5 Grendel out to 1000m. If you have new information comparing factory loads, I'd be interested in learning more about it.

autobahndriver
July 20, 2004, 08:41 AM
The Ballistics table above is correct: Yes, when you consider terminal energy the the 7.62 M118LR round delivers more energy at under 1000m ranges than the 6.5 Grendel (superior as you stated above). The 7.62 NATO M80 is surpassed by the 6.5 Grendel at 600m+ in energy delivered.

The 6.5 Grendel, on the other hand, is superior in drop, drift, and accuracy at all ranges.

It is a trade-off:
6.5 Grendel advantage 50% less recoil (7lbs vs. 14lbs)
6.5 Grendel advantage higher BC, less drop, less drift, better accuracy.
6.5 Grendel advantage less ammo weight.
6.5 Grendel advantage can be used with existing M16/AR15 lowers.
7.62 NATO M118LR advantage 19.8% more energy at 300m, 17.9% more energy at 1000m.
7.62 NATO M80 toss up vs. 6.5 Grendel: 6.5 Grendel 9.8% more energy at 1000m, 7.62 M80 13.8% more energy at 300m.

Not a bad trade in my opinion.

Grendelizer
July 20, 2004, 01:58 PM
TODD3465 wrote: "The makers of the 6.5 can blow their horn about Blackwater testing it all they please but the 6.8SPC round is what is being used by the military not the 6.5."

Todd, I've checked and doublechecked with my sources and the 6.8 SPC is NOT "being used" by the military. Furthermore, a Remington employee emailed this on July 6, 2004: "The round is NOT being used overseas by anyone despite what you might read." (Check it out for yourself; search this forum for the thread "More 6.8SPC Info.")

And let me be clear: I'm not against the 6.8 SPC being used overseas. If it is, it is. Let the facts stand. But I'm very much against promoters of the 6.8 SPC IMPLYING that it's the hot, new military round in order to SELL STUFF to impressionable guys who want to be cool.

Todd also wrote: "Right now a major ammuntion company (Remington) is starting to crank out the 6.8SPC and they have 3 versions of the ammo that will be available to civilians pretty soon." What's your source, Todd? Remington's advertising? Wait, they themselves are not even advertising it! The gun rags? Months ago, Gary Paul Johnston wrote in Soldier of Fortune that Remington can't make it fast enough. Are you one of the millions who've bought it up? "No," you say, "but the military's been buying it all!" Are you sure? Then why did the Remington source say (this July!), "The 6.8 thing is moving along but slowly. The only significant ammo we have sold has been to Barrett as far as I know"?

Well, I'm not going to get into what my sources say about the future of the 6.8 or what my personal opinion is, but let me give you some advice: You'd do well to wait on buying an 6.8 SPC gun or upper until you know FOR SURE that ammo is definitely on the shelves. That's all. If it shows up, it shows up. If it doesn't show up and you're stuck with an upper, don't come whining to me!

John

P.S. If your adoption of the 6.5 Grendel for yourself depends on whether some special operators are using it, then let me remind you that the 6.8 SPC isn't the only game in town. I am allowed to say that the 6.5 Grendel is being used by "select members of the military community."

TODD3465
July 21, 2004, 07:49 PM
You can try and push the 6.5 Grendel all you want but your just ignoring what SOCOM wanted in a cartridge.

And as far as I know NSWC-Crane did not include the 6.5Grendel in it's list of calibers for an improved SOF combat rifle.

Here's a link look for yourself:

http://www.thegunzone.com/556dw-5.html


Go down a little more than half way and you'll see the spec sheet for the proposed rifle

Then just go further down to see mention of the 6.8SPC as the chosen round.

sumpnz
July 21, 2004, 08:19 PM
All it says is that the round had been "unveiled" and is intended for this use. It doesn't say that will be chosen, let alone that has been chosen, to replace 5.56NATO for SOCOM.

I'm not trying to put down the 6.8SPC, as I do see it as significant improvement over the 5.56mm round, but we just simply don't know what, if anything has or even will be chosen in the next 10 years to replace our venerable poodle-shooter.

I do, however, stand by my assertion that the 6.5 Grendel will win out in the "civilian" marketplace as a target shooting, hunting, and SHTF round when compared to the 6.8SPC. That, of course assumes that the military adopts neither cartridge. If they do choose one of those rounds, the other will likely fade into obscurity barring some marketing blitz to get it going on a commercial scale.

autobahndriver
July 22, 2004, 02:50 AM
The latest news from The Gun Zone on the SCAR is:

NSWC-Crane releases "Draft Performance Specification: SOF Combat Assault Rifle Light." The caliber conversion requirements for the SCAR-L have been removed in favor of optimizing the weapon for the use of 5.56x45mm ammunition. (The proposed caliber conversions, such as 7.62x39mm, are instead intended to be passed along to the larger 7.62x51mm SCAR-H.)

In addition, their performance threshold is 1.0 MOA at 300 yards and performance objective is 0.25 MOA at 300 yards. Original performance objective was 0.5 MOA at 400 yards - don't know if this is still in effect.

If they change again and allow other than 5.56 to be looked at, the 6.5 Grendel has the best ability to meet the performance objectives! The 6.8 SPC is only making the cutoff threshold currently.

Unfortunately, the current plan is to go with 5.56 for the light weapon:(
Once again no real look at improving the 5.56.

The Grendel may have a shot at the heavy version (SCAR-H) but the 6.8 SPC has no chance as it cannot compete with anything at long range.

Zak Smith
July 22, 2004, 11:09 AM
What requirement does the SPC "only [make] the cutoff threshold"?

Bullet drop is orthogonal to accuracy.

-z

Das Pferd
July 22, 2004, 11:43 AM
My head is killing me. After do many searches, all I see is people quoting ballistics etc. I know nothing about ballistics. Can someone do a side by side of these two rounds in laymans terms?

Zak Smith
July 22, 2004, 11:53 AM
Very roughly, the 6.5 Grendel shoots a narrower bullet of similar weight to what the 6.8SPC shoots. The narrower profile of the 6.5 Grendel bullet means the ballistic coefficient (BC), a measure of how easily it slips through the air, is higher. The 6.5 Grendel will lose velocity at a slower rate than the 6.8SPC, and consequently, the 6.5 Grendel will have less drop at the same distance vs. 6.8SPC. The difference is academic within 300 meters, but starts to add up at 500 meters and beyond.

As an analogy, you could think of 6.5 Grendel to 6.8SPC kind of like miniature versions of 7Mag vs. .30-06. With a 150gr bullet, both are right around 3000fps, but the 7Mag's bullet is slimmer and it retains velocity better and has less drop.

I think we're still waiting for good terminal ballistics data on te 6.5 Grendel, but some with experience in FBI-protocol gel tests believe the 6.5 will have a longer "neck" (before violent expansion/tumbling) in the wound profile.

-z

autobahndriver
July 22, 2004, 12:19 PM
From what I've read the 6.8 SPC is shooting at 1.0 MOA at 300 meters - the cutoff threshold.

Doesn't matter anymore...the SOCOM requirement is now a light version that must be in 5.56 and a heavy version that is in 7.62 and can take other calibers for long range shooting.

From Remington press release:

"...The 6.8mm Remington SPC, (Special Purpose Cartridge) will be offered in three versions for 2004, including Remington's new Premier® Match, line of ammunition. The 115 grain MatchKing® BTHP bullet will deliver a muzzle velocity of 2800 fps and 2002 ft-lbs of energy while providing low felt recoil and 1 MOA accuracy at 100 yards. The 6.8mm Remington SPC will also be available in both BTHP and Metal-Case 115 grain versions..."

On the recent SOF article extolling the virtues of the 6.8 SPC:

Firing was limited to 25 yards, so no accuracy data was obtained. Johnston expects 1 MOA accuracy, equivalent to a PRI 6.8mm rifle he has fired.

autobahndriver
July 22, 2004, 12:29 PM
Quote from Das Pherd: "My head is killing me. After do many searches, all I see is people quoting ballistics etc. I know nothing about ballistics. Can someone do a side by side of these two rounds in laymans terms?"
____________________________________________________

Basically the two bullets are almost the same in diameter but the 6.5 is a little longer and heavier bullet.

The complete cartridges weigh the same and have case heads about the same size.

Almost the same bullet right???

Wrong...the higher BC of the longer round makes a big difference.

While both show very little difference in velocity or energy delivered at short ranges (under 300m), the longer 6.5 round keeps more velocity as it travels further.

By keeping more velocity, the 6.5 has more knock down energy at long range.

The 6.5 is not effected as much by wind at long range.

The 6.5 does not drop as far at long range (don't have to adjust scope as much or worry about how the angle of shot will effect your trajectory as much).

I'll try and do some graphics and post sometime to illustrate the differences.

Grump
July 22, 2004, 01:10 PM
Isn't the 6.8 SPC just a 5.56 necked up to 6.8mm? The Grendel is a larger case diameter, adapted (not adopted) from the 7.62x39. That means more powder, more reserve horsepower.

I'm still not sold on the 144-gr 6.5mms. It's virtually the same amount of metal overall as the M80 ball bullet, and has a much more loopy trajectory. Goes to slow for me. I would *guess* that it would take longer to flip over on the terminal ballistics side of life.

Zak Smith
July 22, 2004, 01:12 PM
Isn't the 6.8 SPC just a 5.56 necked up to 6.8mm?

No. It's a shortened .30 Remington case.

-z

autobahndriver
July 22, 2004, 02:02 PM
Grump Quote: "I'm still not sold on the 144-gr 6.5mms. It's virtually the same amount of metal overall as the M80 ball bullet, and has a much more loopy trajectory. Goes to slow for me. I would *guess* that it would take longer to flip over on the terminal ballistics side of life."
_______________________________________________

What do you think about the 123-gr 6.5?

Saw a recent posting on another unnamed forum (membership rules) showing the 144-gr having a drop of -355.15 at 1000 yds with 100 yd zero.
It shows the 7.62 NATO 175 OTM Sierra at -397.84 at the same dist.
Velocities are 1411 for the Grendel and 1222 for the 7.62 at 1000 yard distance.

sumpnz
July 22, 2004, 02:21 PM
I'm still not sold on the 144-gr 6.5mms. It's virtually the same amount of metal overall as the M80 ball bullet, and has a much more loopy trajectory. Goes to slow for me. I would *guess* that it would take longer to flip over on the terminal ballistics side of life. If you look at the ballistics chart, the 144 grain 6.5mm starts to have a significant advantage in drift over the M80 by 400 meters, though the difference in drop is academic until you get out to about 900 meters. In terms of velocity, by a little over 400 meters the Grendel has caught up to the M80, and thereafter is faster. Terminal effects are still a ?.

However, I think the 123 grain 6.5mm is really the better comparison to the M80. The 144 grain 6.5mm is really better compared to the 175 grain Long Range 7.62mm. Because 123 grain Grendel round 24 grains lighter than the M80, it will take a while for the energy to catch up, but the energy really is more of an academic measurment anyway. In that sense, so long as it has the energy to get the job done, it really doesn't matter if something else has more energy. Therefore, in this comparison, drop, drift, and retained velocity matter more. But at any rate, the 123 grain Grendel starts off only 100 fps slower than the M80, and by just 200 meters is already going faster. Somewhere between 500 and 600 meters the 123 grain 6.5 takes over in terms of energy from the M80 and by 600 meters it has a 155 fps advantage. In terms of drop and drift, the 6.5 starts to have a noticable advantage by 700 meters and 400 meters respectivly over the M80.

schromf
July 22, 2004, 03:09 PM
Just being contrary here, but has anybody though that the "if" of either of these rounds acceptance, might untimately hinge on preformance in the SAW platform? 500-600 yds is the real practical limit of expectations in the M16/AR platform. But if they modify a SAW for either of these rounds and 800+ yards is going to evaluated.

Personally I don't put much hope in acceptance of either round, and when and if they do I certainly hope that it does not skip the testing cycle in the evaluation.

From the very high level, I would lean towards the 6.5 option. But that doesn't mean that a better mousetrap might be the 6.5mm bullet on the SPC case design.

The good news is the bureaucracy is looking at other options, but what the final solution will be once it runs through that cycle, I wouldn't even venture to guess.

Grendelizer
July 22, 2004, 03:56 PM
Schromf, on May 6, 2004, TX65 posted on THR: "A M249 project is already underway on the 6.5 Grendel."

You wrote: "A better mousetrap might be the 6.5mm bullet on the SPC case design." The 43mm SPC case is a poor fit for an intermediate cartridge in the AR form factor because it limits one to short bullets with their corresponding degradation in trajectory, drift, and penetration. If you want a short bullet in the 6.5 Grendel, you can certainly do so if you choose, but you can also use longer bullets with their corresponding benefits.

John

Tony Williams
July 23, 2004, 03:48 AM
My head is killing me. After do many searches, all I see is people quoting ballistics etc. I know nothing about ballistics. Can someone do a side by side of these two rounds in laymans terms?

If you want to broaden your education a bit :) you could try reading up on basic ballistics here: http://www.quarry.nildram.co.uk/ballistics.htm and on assault rifle ammo (including some discussion of 'ideal' types) here: http://www.quarry.nildram.co.uk/Assault.htm

Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion
forum (http://forums.delphiforums.com/autogun/messages/)

Zak Smith
July 28, 2004, 03:25 PM
Since you 6.5 Grendel guys are reading this thread, I have a request...

I am looking from some actual first-hand chrono data for 6.5 Grendel fired from an 18" barrel, with the 108 - 123gr bullets. Not what you've heard, not from a 24" barrel.

If you don't have that, data from any barrel from 16-20" would do.

thanks
Zak

Grump
July 29, 2004, 09:47 PM
Me Too!!!

Yeah, I want to see our fellow THR dudes' and dudettes' actual chrono data....for BOTH the Grendel and the SPC.

Zak Smith
July 29, 2004, 10:14 PM
I have a bunch of 6.8 data from an 18" barrel, but only with reloads and preproduction ammo. I don't have any actual production ammo yet. I can post it here or in a new thread.

-z

10shooter
July 29, 2004, 10:42 PM
I have two questions about the 6.5mm Grendel. Does the short stubby case length cause any feeding issues? And the width looks like it also would prohibit any true staggered magazines to fit the AR platform. I've been looking at both cartridges and would feel either is an improvement over the 5.56.

nvcdl
August 1, 2004, 12:21 AM
While I am fond of 6.5mm bullets for long range shooting I believe the 6.8
round created the most effective wound profile. Makes sense as it is a slightly larger bullet. It is a very efficient .270 light. - not ideal for elk but more then adaquate for deer size game.

I expect that this cartridge will become popular for civilians - it will allow the ar-15 owner to purchase a 6.8 upper to upgrade their 5.56 defense/varmit rifle to a deer rifle capability. End result - more "black rifles" will be seen in the woods during hunting season.

atek3
August 1, 2004, 01:43 AM
While I am fond of 6.5mm bullets for long range shooting I believe the 6.8 round created the most effective wound profile

Actually no. The designers started with the 43 mm SPC case, and picked the most effective bullet for that case, which was a stubby .277 cal bullet. Starting with a different case would give a different result.

atek3

Zak Smith
August 1, 2004, 01:50 AM
Who has documented results from testing 6.5 Grendel in calibrated ballistic gelatin?

Grendelizer
August 1, 2004, 10:33 AM
Zak, a certain suite of tests are scheduled for August 10. It is anticipated that some of the results will be made public, assuming that those who are paying for the tests are agreeable. I will post as much as I can.

This whole intermediate cartridge "movement" is a good. My theory remains that bigger bullet holes are better, and it's worth paying a slight weight and ammo reduction penalty for the increased wounding, range, and penetration. "Let the air in and the blood out." With the 5.56 it's already become standard practice, as I understand it, to "double tap." So instead of using one 265-grain 6.5 Grendel 123-gr cartridge, you've used two 182-gr 5.56s for 364-gr weight. (One 7.62 M80 weighs 386-gr.) Somebody might argue that even if we were using 7.62 they would still double tap, but my suspicion is that the practice arose in response to the 5.56's performance.

In combat, almost always your enemies are going to be behind cover. If every infantryman were given an intermediate cartridge with a better ability to penetrate cover than 5.56, then enemy casualties must increase as they are denied proportionally more cover. Fewer places to hide means more enemy casualties. And when they're all clustered behind some particular piece of cover that your better-penetrating bullets have herded them to, it's time for an airstrike! ;) At least that's my theory, the military guys can respond.

John

nvcdl
August 1, 2004, 10:40 AM
Yes - you are correct - they did not pick the same case bullet as the Grendel. I don't think their objective was to pick best long range target round - but rather to obtain a more effective manstopper within expected combat ranges. I expect that even if they used a differnt case a larger diameter bulet would have produced better wounds (at least for humans - a 6.5 would be a far superior big game bullet for penetration from rear quarter, etc).


atek3Actually no. The designers started with the 43 mm SPC case, and picked the most effective bullet for that case, which was a stubby .277 cal bullet. Starting with a different case would give a different result.

Zak Smith
August 9, 2004, 10:12 PM
Here's what I predict. Please correct me if you have chrono data that significantly differs:

The 108gr Sencar in 6.5 Grendel:

24" bbl - 2700 fps
20" bbl - 2600 fps
18" bbl - 2550 fps
16" bbl - 2477 fps

-z

TX65
August 11, 2004, 10:35 AM
Here is what is measured on Oehler 35P chrono for the 108 Scenar

24 inch 2750 fps at 49,600 PSI - 2.25" OAL using AA2460, CCI 450 primer
18.5 inch 2700 fps

As far as terminal ballistics tests, they have been done and the appropriate parties are already in possession of the results and considering the possibilities for their applications.

The FBI test protocals are not same as the military. One series relates to law enforcement with their unique requirements and restrictions, the other is bound by an entirely different set of requirements and restrictions.

Edited To Add- There was a 30 degree difference in ambiant temp on the two days the different barrel lengths were measured - the 24 inch barrel was measured on the cooler day so velocity of the 24 inch would be closer to 2800 fps had they both been measured on the same warmer day.

sumpnz
August 11, 2004, 12:22 PM
You only lost 50fps going from a 24" to an 18.5" tube? I really like the Grendel, but color me sceptical.

Zak Smith
August 11, 2004, 12:36 PM
I, too, am really skeptical that 6" of barrel only yields 50fps in a cartridge with a volume : bore ratio like 6.5 Grendel.

I would expect this kind of result in a low volume case with a fast powder because the residual pressure from 18-24" would be very low.

-z

TX65
August 11, 2004, 12:40 PM
Zak & Sump,,,

Read edit in original post,,,, difference in ambiant temperature...

sumpnz
August 11, 2004, 01:13 PM
OK, that sounds a bit more reasonable, though I would still expect more than 100fps difference, probably more like 150-200fps. As I understand it, with these high intensity overbore cartridges you should expect (rule of thumb) about 30-40fps difference for each 1" of change in barrel length. At a 5.5" difference that would indicate 165-220fps as the expected difference.

What I'd like to see is some chrono data for the 108, and 123 grain bullets from the 18.5" and 24" tubes from the same day. Say 5-10 shot averages, with standard deviation and 100 yard group sizes if possible.

Edit to add: I'd also like to see the 6.8SPC tested alongside the 6.5 Grendel so that we can do an apples to apples comparison without trying to account for changes in temperature, humidity, and pressure.

TX65
August 11, 2004, 02:04 PM
Sumpnz,

The 6.5 Grendel, like the 6 PPC and 22 PPC are not high intensity overbore cartridges. As a rule of thumb, 25 fps is a good approximate, but that is not always correct.

TX65

Grump
August 11, 2004, 02:09 PM
I mis-spoke a bit:
Grump Quote: "I'm still not sold on the 144-gr 6.5mms. It's virtually the same amount of metal overall as the M80 ball bullet, and has a much more loopy trajectory. Goes to slow for me.

that should be a more loopy trajectory as compared to lighter bullets in the Grendel, not as compared to the M80 Ball. I'm lobbying for as much IMPROVEMENT over M80 as we can get! Well, without winding up with a .243 Winchester with short barrel life...

In general, the costs, materials and velocity loss of even the 123-gr 6.5mms may bring not enough* advantage over performance with the 100-105-gr bullets. The best compromise may lie somewhere between 100 and 123 grains of bullet...

We got some Grendel chrono data from different days--who has some SPC data?

TX65
August 13, 2004, 07:13 PM
Did some 6.5 Grendel range testing today using an Oehler 35 Chronograph

Shooting the Lapua 100 Scenar using N530, magazine length loading

28 Inch Barrel - 2900 fps
24 Inch Barrel - 2850 fps

The Nosler 100 Ballistic Tip and 100 Grain Partition were running 2850 fps out of a 24 inch barrel.

Edited to add..

The Lapua 100 Scenar has a .444 BC and is currently on the shelf at numerous dealers.

In an 18.5 Grendel, the 100 Scenar performed at 2775 fps using N530 in a magazine length load.

Zak Smith
August 13, 2004, 08:13 PM
We got some Grendel chrono data from different days--who has some SPC data?

The 6.8SPC Load Data page is linked off my FAQ. See below ...

The control point is the preproduction Remington 115gr shoots 2700-2750fps from my 18" bbl. Note that the BC of the 110gr VMAX is 0.37.

-z

TX65
August 13, 2004, 08:48 PM
Zak,

Since Remington used an OEM powder that is not available over the counter, do you have chrono data from loads you have done using cannister powders (ex,, H335, N133....) and bullets that are available to end users for magazine use (ie ... Hornady 110 VMAX)?

Also, please tell use what type of chrono you use, whether it is a triple or double screen and what screen spacing you use.

TX65

Zak Smith
August 13, 2004, 08:53 PM
TX65,

That is eactly what you'll find on my Load Data page (http://www.demigod.org/~zak/firearms/6.8SPC/loads.php) if you follow the link as instructed. :D

Before I am innundated with questions here, please be sure to read it all carefully.

-z

Zak Smith
August 13, 2004, 08:56 PM
The two chrony's I used for much of that data were a Shooting Chrony Beta Master model, and a Prochono Digital. Default screen spacing. I always shoot some BH75 from my 223 AR15 to make sure they're working.

I wll pony up for a Oehler and build a chrono box after RM3G and ITRC...

-z

TX65
August 13, 2004, 09:08 PM
Thanks Zak, it helps me understand how you measure velocity...

Reading your data, your best velocity with a handload and the 110 VMAX is 2635 fps from an 18 inch barrel.

Would you happen to have the interior width of the case at the base of the powder column?

Zak Smith
August 13, 2004, 09:16 PM
Reading your data, your best velocity with a handload and the 110 VMAX is 2635 fps from an 18 inch barrel.

Well, let's put it this way-- within the limits of the tools I have available, that's the best I have some reasonable assurance is "safe." I have gone well above these, but without some actual pressure data, I'm not going to keep doing it.
I have only listed loads I have personally chrono'd in my rifle and the internal ballistics modeling reports less than MAX pressure. This doesn't guarantee it is under MAX pressure, but that along with the lack of physical indicators of overpressure is a pretty good set of clues.

If your comments about QuickLoad being inaccurate with regard to pressure apply to 6.8SPC, then these could be really conservative. I have no way to tell.

Would you happen to have the interior width of the case at the base of the powder column?
Sorry, no. I don't have the right kind of saw to section a case. The powder volume is around 35.4gr H20.

TX65
August 14, 2004, 10:58 AM
Zak,

You strike me as an intelligent guy so I assumed that the loads you posted are safe... The purpose of my question was to learn of the performance obtainable using off-the-shelf components available to everyone.

Regarding the width of the powder column, my interest in that number is to calculate bolt thrust levels at various pressure levels.

From your measurement of H20 capacity, the 6.5 Grendel and 6.8 SPC have the same H20 capacity.

In a discussion I had with the developer of Quickload, the internal ballistics calculators that allow you to estimate pressure and velocity are just estimators / indicators to give you some ideas of where a load is headed. As you and I discussed offline, Quickload cannot take into account variables in throat dimensions especially on non-SAAMI spec chambers.

Zak Smith
August 14, 2004, 01:46 PM
My point about velocity & safety was that: I'm pretty sure the max loads I'm posting are safe, but it might be that we can go higher safely with available components. Until we have pressure barrel data, I'm staying on the safe side.

I haven't actually measured the water capacity myself. That was a number I got from someone else.

I sectioned a case normal to its axis. The inside width at the bottom of the case is about 0.354", but that's just above the curved transition from base to wall. The case walls are approximately 0.033" thick 0.325" above the case head.

http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/small/131_3113_img.jpg [ link to larger image ] (http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/?medium=131_3113_img.jpg)

http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/small/131_3114_img.jpg [ link to larger image ] (http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/?medium=131_3114_img.jpg)

http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/small/131_3115_img.jpg [ link to larger image ] (http://apollo.demigod.org/~zak/DigiCam/6.8SPC-case/?medium=131_3115_img.jpg)

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