Out of a 12" barrel, how do the 6.5G and 6.8 compare?  Apples to apples, at what range does the 6.5 overtake the 6.8 in velocity?

Has anyone done time of flight comparisons between the 6.5G and 6.8?  (This is really more of an academic inquiry.)  For instance, if two different bullets leave their barrels at different velocities, and one overtakes the other at 400 yards with respect to retained velocity, the initially faster one will reach the 400 yard mark faster.  Just curious.

A 123gr A-Max with a .510 BC at 2200 fps from a 12.5" 6.5G barrel and a 120gr SST with a .400 BC from a 12.5" 6.8 barrel equal out on velocity at 350 yd's @ 1702 fps but the A-Max doesn't overtake the SST on drop until ~750 yd's where the 6.5 A-Max has 235.62" of drop and the 6.8 SST has 237.12" since at 700 yd's the 6.8 still has a little over 1/2" less drop(192.85" vs 193.47"), the 6.5 does have about 7" less drift at 750 yd's with a 5 MPH cross wind though.

With a 200 yd zero both rounds will be in the dirt by 500 yds.

They look very similar, 6.5 is the dotted line and the 6.8 is the solid line in the pic below if you can make out the pic.

Based on your data, it appears that the 6.5G doesn't match time of flight until beyond 625 yards.

The Hornady 6.5G 123gr A-Max ammo has a MV of 2350 fps from a 16" barrel and shows a loss of ~150 fps going to a 12.5" barrel and the Hornady 6.8 120gr SST has a MV of 2460 fps and shows a loss of ~110 fps going to a 12.5" barrel since it's a little more efficient than the 6.5G.

I have seen both of these loads chrono'ed on the same day from my 12.5" 6.8 and a friends 12.5" 6.5G so that is where I got my numbers, I'm sure everyone get different results.

I was under the impression that the 6.5 out performed the 6.8 in distance. From the data above it does not look that way. Is this true that they are about the same?

The Gap is closing rapidly.  When SSA releases the Berger 140 VLD, going 2400 from a 16" barrel, with BC of .487, things will start to look interesting,  With the newest higher BC bullets, and the 6.8's ability to throw similar weight projectiles faster, the Grendel's former perceived "advantage" is all but gone.

I personally now shoot 135 SMK's out of my 6.8 bolt gun (with 18" barrel) at 2420 FPS.  Of course, a deer or hog cannot tell the difference, and I still think the Grendel is better than 5.56.  However, the 6.8 has quite similar performance at longer ranges with these better bullets than what we had at the beginning.  The Grendel bolt face is only rated for 52K or so PSI, so the limit is quite a bit more concrete  than with the 6.8.  I'm not recommending that people shoot 60,000 PSI loads in SAAMI spec 6.8's but there is more performance there to be had in SPCII's with proper specs, with these slightly heavier  or VLD bullets, such as 120 SST, and 140 Berger VLD.  At 55,000 PSI, I believe Art Kalwas got the 140 VLD into 2.295" OAL, and still got 2400 FPS.  I got them a little faster in my testing, but I will say right off the bat, that I loaded them to bolt gun lengths of 2.35."


With all that said, if you still shoot at things at 500+ with an AR-15 you are either

1) a hot-shot

2) a competitive shooter

3) wasting ammo for fun (nothing wrong with that )

The Grendel and 6.8 are so close its almost a wash, but I still think I get a little more versatility with 6.8.  I can shoot 85 TSX at 2900 FPS in my 12" barrel, 95 TTSX at 2750, or the 120 SST at 2350.  I can then turn right around and shoot the 135 SMK at 2400, the 95 TTSX at 2900 or the 110 TTSX at 2700 from my 18" bolt gun. (hand loads, of course)

Lots of bases covered there.

I think that  the efficiency gap between the 6.5 and 6.8 increases as you decrease barrel length.  Therefore as barrel length decreases,  the 6.8 holds an edge at a longer distance.

Several years ago, the 6.5G's trajectory advantage started around 400 yards, and when I got in the game in 2009, it was closer to 500. Now, it is closer to 600-650 with the 120 SST.

Art from SSA just announced that he has tested and chronographed a load with a new 140gr Berger VLD that will be loaded to 2400fps from a 16" barrel. The b.c. is .487 on that projectile. That puts the yardage even further out.

The 6.5G continues to have an edge with windage.

I am speaking of 16" barrels here. He says the 18" should be around 2500fps.

Per Art, from 68forums

Default

   The rounds were shot from a 1-10 and 1-11 twist semi autos, the range we were at only goes to 800, all ballistics were from a 1-10 twist 16" barrel. From a 18" I would guess the velocity will be around 2,500 FPS. With the 1-10 the round is still super sonic pass 1,000. We loaded then out to 2.295 so you need to have the right mag.


   Art - SSA

Dang, HTR is fast on the trigger today.

Can the 140gr Berger VLD be used in AR mags?  If seated more deeply to enable that, what will the anticipated velocity be for the 140gr Berger VLD in a 16" AR rifle?

Read above.

It is seated at 2.295 so it is capable of using PRI and the new C Products Defense mags. All of the old SAAMI stuff, the ammo, the mags, the barrels, are all falling away now. The cartridge is back to where it was designed to be all along.

The velocity is 2400fps from a 16" barrel.

Art, the owner of SSA ammo, tested it already. Hopefully it will be out soon.

"I believe Art Kalwas got the 140 VLD into 2.295" OAL" sounds less than positive.

Can anyone confirm?

I was planning on doing a 24" 6.5 G. The main reason was to get into long range target AR shooting(aka want to build a new rifle). I am looking at the 600 Yard's plus. What do you guys think? Should i stick with the 6.5?

Just a couple of posts above yours, I quoted Art from the thread in 68forums.


Per Art, from 68forums

Default

The rounds were shot from a 1-10 and 1-11 twist semi autos, the range we were at only goes to 800, all ballistics were from a 1-10 twist 16" barrel. From a 18" I would guess the velocity will be around 2,500 FPS. With the 1-10 the round is still super sonic pass 1,000. We loaded then out to 2.295 so you need to have the right mag.


Art - SSA


This will be offered by SSA as a factory load

Thanks.  So with this new load, can the 6.5 really claim superiority at long range?  At what range?

If you plan on shooting 600 plus and you're comfortable with a 24" barrel, I would go with the 6.5G, or the .264. There is another caliber out there as well that you should check on. The 6.5 BR and 6.5BRX from AR Performance that Harrison makes will get 150-200fps more from the same projectiles as the 6.5G, but it is a wildcat, and some effort is involved. So if this is your first go at an AR, for your purposes the Grendel might be you.

What is the average muzzle velocity for a 120sst from a 12in gun?

I ran the ballistics for it at 2350fps against the 2330fps from the 123amax and the values don't look quite as close as above.

     If was planning to build one, I'd go head and do it. I have a 16" 6.8 and a 20"

     Since, I am planning to build but I am waiting for Harrison barrels to arrive.

     RJ

I wonder how it will perform in my arp 18" 12 3 groove barrel?
 

I wish this was my first AR. I have covered all my bases as far as AR builds go. I have done so many 5.56 that i told my self i was not going to build anymore. Then on top of that i have AR's in 5 other caliber's. I just haven't done anything in the 6.5 or 6.8 area. I think i will stick with the 6.5. I think if i went with the 6.5br i would have to get into reloading.

Art said 2500fps, and should stabilize.

Are you guys talking about loading the existing 140gr .277" Berger VLD in a 6.8 within PRI mag-length COAL limitations, or a 6.8 specific 140gr VLD?  That's a lot of bullet for the 6.8 case, just as the 140gr 6.5mm VLD is a lot of bullet for the Grendel case.

If I were going to use one of the VLD's of heavier weight in the Grendel, it would be the 130gr VLD, which will fit to COAL, and even a 2.300" COAL in at least one of my CProducts mags.  I just tested it last night, since I have been getting great results with 130gr VLD's in my .260 Rem AR10.

When I compared the ballistics between my .260 Rem and .270 Winchester, both with 140gr VLD's, I needed 250fps more muzzle velocity in the .270 to match the .260 at 1000yds, and the 6.5 still has less wind drift.

For the 12.5" guns, it makes more sense to me to stick with the 100gr class bullets, since keeping a carbine of that weight on-target at 500yds definitely would be a challenge, and would involve optics that outweigh the small profile of a carbine of that profile.  Maybe the 9.25" long GRSC 1-4x wouldn't make the gun crazy in profile.

The advantage with the Grendel from a reloading and terminal ballistics perspective is that there are way more projectiles to choose from, and higher sectional density pills that will penetrate deeper, with slightly more retained energy at distance.

The advantage of the 6.8 right now is more factory-loaded ammo selection.

For the shooter, they won't realize any trajectory differences within 250yds, and even at 300yds, the two are within inches of each other.  I still feel that the Grendel is stacking the deck in your favor for hunting, with longer projectiles that are more likely to defeat bone and reach deeper into the animal.

LRRP, it is a factory load that was tested just a bit ago, and getting ready to go into production.

Silver State Armory, SSA, is the manufacturer.

Factory loaded at 2400fps from a 16" barrel. This particular Berger VLD is short enough to fit into the case.

Grendel is more versatile as far as brass.  Fire form x39 and boom, you got brass.

Interesting. I'd like to see it. Can you (or anyone else) post a photo of that? Every VLD I've seen had a very long ogive, so I can't imagine how one would fit and have only 2.295" OAL.

Shit Stan, I've posted the link from 68forums twice already, as well as direct quotes from Art. Just go look over there at the Long Range thread in the Reloading section.

Ah fuck it. Just for you Stan.

http://68forums.com/forums/showthread.php?27533-Long-Range

How fast will the 6.5G push a 140 grain bullet from a 16" barrel?  I think you need a 24" tube to reach 2,400fps don't you?

i'm running a 12.5" on my 6.5G and IIRC, was getting 2330-2350fps with factory Hornady ammo, and about 2300 with the Wolf

Zeroed at 50 and still right on at 100 yards.  about a 1-1.5-inch drop at 150 and about a 3-4-inch drop at 200 based on shooting it.

The 6.8 would be a better choice for a SBR rig.

Here ya go, you have NO experience with it yet the owner of Silver State Armory that makes the ammo says he is loading it and you doubt it.

It's stanc, you expected less?  

I guess that's true.  I really like the ability to take cheep brass and make Grendels out of it  

I use x39 from Winchester and PRVI.  Great for shooting cans.  Save the Lapua and Nosler BTs for the Hogs.

Just curious...is the because the 6.8 has more support behind it and thus a faster evolution or is it because of inherent differences between the cartilages allows the 6.8 to evolve?

//edit for emphasis

There was absolutely no support for the 6.8 for a long time. Remington made a mistake on the chamber and actually made a dangerous chamber when using the original spec ammo  and submitted it to SAAMI. They downloaded the ammo to make it safe, rather than correct the error in the chambers. They then proceeded to pull everything out from under it to kill it. Some of the guys that started the 68forums caught the mistake, and knew that the caliber as drawn by Chris Murray was very potent for not only mil, but hunting as well. They went about redesigning the chambers and combining them with the right twist barrels, and got the cartridge back up to spec. That is the Spec II ( actually closer to the Original design ).
Those guys pushed it. It was ignored by all but a small cottage industry of boutique shops, like AR Performance, and a few others. Hunters began to notice that it was very effective on game even out of the ar15 platform, and staring buying them up. It grew despite having no industry support, not because of it. Now it has tons of industry support because there is money there. Additionally, all of the bullets that were originally used were all .270 bullets, which weren't really the best for the magazine length restrictions, and most were design to operate at .270 velocities. There are a good number of bullets now just for the 6.8 to open all the way down a 1600fps. The 140VLD is one, and that takes it to 525 yards from a 16" barrel.

In no particular order
You can thank
Harrison Beane-AR Performance
Hi Tech Rancher
Art at SSA
Tim W
And a few others for pushing this thing to where it is now.

At first, ammo companies were afraid to load to the new ( actually old ) specifications due to liability reasons of possibly being used in the Remington type ( screw up ) chambers.  SSA was the first with the Tac and Combat loads. Wilson is on board now. There is a small company Good To Go that does as well.

The 6.8 was not an industry effort, but an effort started by soldiers in the 5th SF to have a better killing tool, and later, by hunters to have the same increased advantages on game. That is one of the main things that drew me to the 6.8 over the Grendel.  I loved the story of how very little it cost to get the 6.8 developed, ( 5K I think ). Just a few good soldiers trying to see to it that their fellow warriors had the best tool available to keep them alive.

I am still hopeful that someone will resubmit ( or submit ), the 6.8 spec II to SAAMI. It can be 6.8x43, or some other variation, .270AR, which is what I would look at with the big hunting following. That will stop the nonsense of the confusion that takes place over the chambers.

So this round is a shooter driven round.

Basically to answer part of your question, the advancement would not have been necessary had Remington not messed it up to start with.

It has evolved so much because it was severely "tuned" down.
Essentially it was like restrictor plates on a race car choking it down. The plates have just been taken off.
Now we're working on better suspensions, running better gas, and other tweaks and tunings to get the most out of the big changes.

Interesting.  thanks for your reply, it was thoughtful and clear...a rare combination.

Shit, my eyesight must be getting really bad. I didn't see any photos there of either the 140gr bullet or the loaded round.

It was really sort of mixed up and scatterbrained. Chatting up an old girlfriend online and typing that was confusing, not to mention that she was recalling some of our "special" times together.

I will give you a link to the development. And then go over and read up on 68forums if you haven't yet to gather more info. Very professional folds over there. The developers are online all the time and are very nice to deal with. Some are here too though.

This link is from Demigod. It is older info, but it's a great insight into the development.

http://www.google.com/url?sa=t&rct=j&q=5th%20special%20forces%206.8%5C&source=web&cd=1&ved=0CEYQFjAA&url=http%3A%2F%2Fdemigodllc.com%2Farticles%2F6.8-mm-spc-cartridge-history-development-hornady-stag-arms-carbine%2F&ei=lQZkT9vhFY3Ntgep3vz9DQ&usg=AFQjCNEnkknu1mOWBBWTV1Nx4gq1LRnCcQ&cad=rja

There are no photos. Just Art saying he tested it,

Stan, sometimes you just have to trust that things are there without photographs.

Man, I just love the level of reading comprehension shown by some people.

I didn't doubt that Art is loading it. If he says he is, I take him at his word. What I said is that I'd never seen a VLD that could be loaded to mag length, so I was interested in seeing what it looks like. Why are you making my query into something it isn't???

I trust it's there. I was just curious to see it. Is that some kind of sin with you guys?

Because of your track record.

Since I feel that I jumped to conclusions here, I apologize, and offer this as a token.



For whatever reason the pertinent info didn't take.

It is the Hunting VLD. #BB27502

Thanks. Appreciated.

I

One irony of this cartidge is that it evolved in the hands of several average people, and virtually no corporate support, in the beginning.   There was input from professionals in the Mil for sure, but had it not been for Tim Hicks of Ko-Tonics, Harrison Beene and Art Kalwas, I'm not sure we would have the cartridge we do today.  Another factor which allows for continued evolution  is the incredible efficiency of the 6.8 x 43 mm case.   Many of the 6.8's common powders can be completely burned in @ 9" of barrel,  hence it's exceptional performance in SBR's, PDW's and carbines.  If youve ever heard a subsonic round using Trail Boss and a 150 grain bullet fired from a suppressed bolt gun, you know what I'm talking about.

The bolt design leaves some strength that the Grendel's does not have, so pushing this cartridge into the 60,000 PSI range, if done by experienced hand loaders with well built rifles, is not breaking guns.  That said, I dont recommend that kind of pressure for high volume fire, but for single, slow fire, the properly spec'ed guns can take it.  Just look at the pressure the Mil is now (purportedly) using for M55a1.  It's said to be 62,0000 psi .  If that bullet works so well, why risk beating up the rifles, when surely there will be high volume fire? Hmmm.  With 6.8, even the rather modest pressure of 55,000 psi produces 95 % of the cartridges maximum velocity potential.

So, you can push the 6.8 more than you can the Grendel.  The high efficiency drives bullets to speeds that seem unlikely for max pressure, and the guns handle this and a litle more with enhanced bolts, like the LMT and ARP super bolt.  Of course you might beat the brass up faster too, but thankfully, components are allowed take less pressure  now that we use a longer throat and different rifling to take max advantage of the full bore area.

Pretty amazing that 58,0000 (same pres as m193) will push 85's to 3050 in 16" barrels, and 140 VLD's are hitting 2400, at 55k in that same carbine.  Thats because new propellants take advantage of that efficiency.  Quite impressive performance when you really think about it.  No matter how many new wildcats we see, there still isn't one that matches the performance of the 6.8, in short barreled rifles, and terminal performance is better than i expected, when I first started loading it and shooting  big hogs with it.  The Grendel is very close in SBR's and still a little better at very long range, but it cannot be pushed much more until and unless bolt design is enhanced with more thickness around the lugs and rim.

6.8 may still have a little room to grow into longer projos.  One method would  the area of bolt gun OAL, which opens up a whole new world of possibilities for it.  

ETA:  6.5 Grendel bolt guns would also be quite interesting

I can't wait to try the 140 in my 20" ar performance barrel.

Pavlovwolf & Hi-Tech Rancher are both right concerning the 6.8.

I would like to add:
1. Being designed for a short barrel & the hog explosion/AR craze, helped the 6.8 allot. (Yes, I know the 6.5G is just as capable, as mentioned by others in this thread.) It is just that the emphasis on the  6.6 has been on long range.

2. IMHO - Part of it is that AA trademarked Grendel & licensed it out for years. Which strangled creativity & made companies hesitant to invest in it. Also, curtailed creativity/experimentation.
So with the removal of the restrictions. The question is; Is it a case of closing the door after the horses are gone? Time will tell.
That is just my opinion about the situation.
6.8 has been open source from the get go. Even chambers have slight variations; SAAMI, SPC II, 6.8 ARP (DMR & DMR-C have ceased) & Noveske Mod 1.


Now, that being said;
I agree with the others.The 6.5G is a fine round! Along with the 6.8. You can't go wrong with either.

How fast can a 16" Grendel push a 140gr pill?

Uh, not quite. I don't know if they are engaging in historical revisionism, or suffering from selective memory, but the truth is that in the beginning, 6.8 SPC had substantial industry support.

Barrett developed uppers; PRI developed magazines; Hornady and Sierra developed SPC-specific bullets; and Remington developed the cases. If it weren't for those companies, 6.8 SPC would likely never have become more than an obscure wildcat.

(Much, much more than $5000 was spent on birthing 6.8 SPC. Steve Holland may have been allocated that amount by 5th SF Group, but five grand wouldn't even begin to pay for development of the cartridge cases, let alone the bullets, etc.)

From my 24" Rem 700 6.8 I'm getting 2650 fps with the factory 120gr SST and with my 130gr hand loads I'm getting 2600 fps, both of these loads have room for more velocity.

If the 140gr VLD's will make 2400 fps from a 16" barrel they should easily do 2600 fps from my bolt rifle, this will make a great longer range cartridge staying supersonic to 1K yd's easy.