I am seeing more Grendels in carbine trim, how do they compare to 6.8 in these shorter barrels?

I have 16 and 12 inch, along with a 20.
My 16 inch I consider my 'General Purpose' rifle as it does everything well.
It's just a 16 inch midlength gas system chrome lined gov weight tube.
Knocks the snot out of stuff up close and at 600 yards.

The 12 inch is my most recent project. So far I am very pleased with it.
Probably end up my favorite of the bunch....carries 1,000 ft-lbs all the way
to 300 yards. Crunch some numbers and think about it.......

Read the FAQ on 6.8 vs 6.5. There is enough information on this topic to keep you busy for a long time.

In general its considered that the 6.8 in superior from short barrels, while the 6.5 has the advantage from longer barrels. YOU need to decide what the rifle will be used for, and select the caliber that best fits your needs.

Yes, it has generally been taken for granted that the 6.5mm Grendel belongs only in long barrels....
but this is false. It works extremely well from 16 inch barrels. In your face performance is very good
and you can still reach out to 600+ yards without issue. I was rezeroing my 16 inch carbine today and
I ran out it out 550 yards on steel. Hornady's new 123 grain AMAX load will expand down to 1600 fps
according to a contact at Hornady. That's 500 yards from a 16 inch gun and over 400 yards from a 12 inch.

I am just starting to work with it from a 12 inch tube and performance is better than expected.
Factory AA loads are pushing a 100 grain Berger OTM at 2,500 fps. Keep in mind, muzzle velocity is
not everything! Performance is. Factory 123 grain loads will retain almost 1,000 ft-lbs all the way out to 300 yards.
That is very impressive.

I think as more work is done with short barrel Grendels people will be surprised at the performance.
I've played a bit with the 10.5 inch guns and think 12-12.5 inches is probably as short as I would
go with this cartridge.

ETA I was testing 7.5 and 8 inch 5.56 AR pistols on the range today along with my 12 inch gun.
After running them across the chrony and crunching some numbers my 12 inch 6.5mm Grendel retains
more energy at 600 yards with factory AA 123 grain ammo than the 8 inch 5.56x45mm has at the muzzle
firing Black Hills 60 grain VMAX

I agree completly. My only AR is a 16in Grendel, and its awesome to shoot.

My reply was meant to be a generalization of sub 14.5in barrels, becasue I'm not sure how short the poster means by "Carbine". Now a days that could mean anything from 16in  to 10.5in barrels. Its in the SBR format that 6.8 really shows its potenial.

I'm pushing 120-123gr. bullets about 2500fps with my 18" Grendel.  According to JBM I'm keeping most if not all of those rounds supersonic beyond 1000yd (scenars and 123 smk).  The 6.5 Grendel has in all honesty redeemed the AR-15 for me.  I was extremely close to going with an AR-10 sized platform but gave the 6.5 a chance before doing so and I've been extremely satisfied.  I've never considered the 6.8 to be of any real advantage over the 6.5.  At close range it's neck and neck IMHO (I find the difference negligible), and at long range the 6.5 dominates.  Why limit yourself?

Personally I'd never take the 6.5 under 14.5".  16-18" barrels are good to go for hunting or whatever you need to use them for out to 300-400yd easy.

I'll let you know as I'm going to start my 18" build later today.

I currently own a 6.8. I am just interested in the 6.5 as well. Thanks for the replies.

I agree with what gunwritr said.  I own both the 6.8 and 6.5 and I have found that the 6.8 is really over rated from shorter barrels.  It is important to remember that it loses a lot of velocity as well when the barrel is shortened.  Not as much as the grendel, but the 6.8 has to work much harder than the grendel to maintain those velocities.  Usually the grendel can catch up in energy within 75-100 yards and past that the grendel just keeps pulling further and further away. But if you are fighting a battle inside a building then the 6.8 has a nominal advantage over 6.5.

Another satisfied 16" 6.5 Grendel owner here,  only other AR's are 16" 5.56, 20" competition H-Bar 5.56 and 3 dedicated AR  22's.  I really like the performance of the 6.5 G out of my carbine with the limited testing I've done.

So what do you guys make of ARP's owner who says the following out to 300 yards with 16" tubes?  

And on a related note, are you really going to be engaging adversaries in a combat situation beyond 300 yards with your purty tricked out 16" carbine?


6.5 Grendel using Bill Alexanders max loads in a 16" barrel- zeroed at 200yds drops at 300yds.
due to velocity dropping below the expansion threshold 300 yds is about max for taking deer or hogs with either caliber.
the same temp, pressure, line of sight and program used to figure all drops in both calibers.
100 Nosler-2600fps––drop 9.4/801 ft lbs
107 SMK-2545fps––––-drop9.5/878ft lbs
123 SMK-2472fps––––drop 9.4/1083ft lbs
120TSX-2472fps––––drop9.8/984ft lbs

6.8 SPC SSA factory ammo 16" barrel
100 Nosler-2700fps––drop9.0/809ft lbs
110 Nosler-2630fps––drop9.0/939ft lbs
110TSX-2630fps––-drop 9.5/856ft lbs ––––––added
6.8 handloads max
100 Nosler 2950fps––-drop 7.4/993ftlbs
110 Nosler 2750fps––drop8.2/1040ftlbs

http://www.ar15performance.com/6_8_misc_info

The info is about hunting. It compares the two inside 300 yards. It says nothing about engaging enemies at all. What enemies? Deer and hogs?
Constructor knows more about these two cartridges than just about anyone. What I make of it is he is answering questions for folks who are considering the 6.8.

Uh ... I said "And on a related note, ..."  Never said that he said anything about engaging enemies.  

Most of us on here like to think of our rifles as optimal for SHTF applications.  Very few people with 16" AR's are hunting with them and also not engaging in long range matches.  So for the most part (I'd venture 98%) that leaves weekend warrior plinkers and short range competition shooters who want to rely on their rifle in the event of a zombie apocalypse.

I think your numbers show the 6.5 Grendel and 6.8 SPC are very similar out of shorter barrels.  The only shots I can see me taking beyond 300 yards are possibly paper/steel targets or varmints.  If you can effectively engage targets beyond 300 yards I don't see to many 2 legged foes standing around letting you shoot at them with your small pop gun.  In a SHTF situation where someone is firing at me I'd like to be able to throw lead back the other direction even if to only allow me to get out of their range.  From the numbers I've crunched a lot of 6.5 G rounds stay supersonic out to 800  to  900 yards even out of a 16" barrel.   The 6.5 G will still deliver 500 ft lbs of energy at 500 yards which would be about the same energy as some pistol/ sub gun  rounds.   For what I wanted in an AR 15 platform it was a choice between the 6.8 and 6.5G.  My son in law had a LW 24" 6.5 G which impressed me so I opted to go 6.5G.  I also liked the ability to fire form 7.62 X 39 brass.   All boils down to personal choice just like Chevy/Ford, Colt/LMT ect.

Sorry bro, misread your post.

I think a long shot could end up being needed in a SHTF situation. I would rather have the ability than not.
300 yards is a long shot with any rifle in a stressful situation. I would guess most real deal killing would be at spitting distance.
The real advantage both of these have in a defensive scenario over 5.56 is barrier penetration, if that is important.

I use the 6.8 for hunting, it is now my only hunting rifle. I left the .308AR world after a short stint.
I still say 5.56 will do 99% of what anyone needs a defensive rifle to do. I won't be shooting 500 yards at turbans...I don't think.....

I can share my data from my 16 inch barrel using factory loads
for a 200 yard zero
Alexander Arms
100 grain Berger OTM-2,723 fps-drops 8.9 and retains 925 ft-lbs at 300 yards, and drops 94 inches and retains 486 ft-lbs at 600 yards
120 grain Nosler Ballistic Tip-2,535 fps-drops 9.6 inches and retains 1,063 ft-lbs at 300 yards, and drops 98 inches at retains 630 ft-lbs at 600 yards
120 grain Barnes TSX-2,494 fps-drops 10.9 inches and retains 916 ft-lbs at 300 yards, and drops 114 inches and retains 481 ft-lbs at 600 yards
123 grain Scenar OTM-2,523 fps-drops 9.4 and retains 1,162 ft-lbs at 300 yards and drops 92 inches and retains 758 ft-lbs at 600 yards

Hornady
123 grain AMAX- 2,463 fps- drops 10 inches and retains 1,068 ft-lbs at 300 yards, and drops 100 inches and retains 664 ft-lbs at 600 yards

These factory loads were chronographed with an Oehler 35P chronograph at 1,030 ft above Seal Level. Min 10 rounds fired per load at
12 feet from the muzzle.

Remember, these are factory loads. Handloading I can pump the velocities up a bit. But I think it's smarter to choose an efficient projectile than to
chase velocity.

I've been told by Hornady that their 123 grain AMAX will expand down to 1,600 fps. This would allow expansion out past 500 yards
from a 16 inch carbine. Gel shots I have seen with this load are very impressive.

regarding the comment of engaging targets at 300+ yards in SHTF.
I would expect engagement distances to typically be very very close.
However, I live in Kansas where its very flat and very open. This ain't
New England. I very much like the ability to bring hate at 700 yards
with a 16 inch semi-auto carbine.

If you can figure out the dope.... 500 yards is a very long shot at a human in a defensive (or offensive) situation. I just don't see shots at much over 100 yards being needed, unless you live out in the West or somewhere really flat.

6.8 is no slouch at 500 either

500 yards is just part way across the backyard for some of us.
Why everyone needs to choose what is best for their own needs.

I wish my backyard was like that.

For most of us, 100-200 is a long shot. 10-50 is much more likely.

One day, I am gonna move to Montana or Idaho....

Bingo, exactly. If SHTF where I am, I doubt I'll have to worry about anything ( or one ) at any range greater than 100-150 yards. If I had to bug out to someplace to the north, longer shots may be necessary. In either case, I built a 20" Grendel not because I plan on engaging hostiles at 600-700+ yards, I built it because I could.   A 16" Grendel does intrigue me if the ammo becomes a bit more reasonable though.

You can get Grendel barrel ballistics on the this website http://www.alexanderarms.com/calnews.htm. As ballisiics wise 6.5mm Grendel kicks ass when compared to 6.8 Rem. SPC. That's IMHO.

Mike

here is my backyard. I guess that explains why I like the Grendel so much.  Oh and this is North Idaho.

That looks a lot like Palouse country. In fact, like the area around Boomershoot, which is north of Orofino.

Bill

It is Palouse country.  Genesee Idaho to be exact.  I am actually attending law school at the university of Idaho but the view and the home is worth the 30 minute drive to school every day.

Knew that looked familiar!!

Beautiful area, a little too much snow, though! LOL!!

Bill

Very excellent point. While I generally deer hunt at less than a hundred yards, I  have a clear line of sight from my house, 300+ yards, in most directions. My AR shots sub-MOA while only being laid across a log that I call my shooting bench. I have a BDC scope for the long range stuff and I hope that my laSer sight and BUiron take care of the zombies when TSHF. LOL

Shot and chronographed both my 16 inch and 18 inch 6.5 Grendels today.  I shot 10 shot groups over my Oehler 35P in a 100 yard indoor range.  The first sky screen was 10 ft. from the muzzle and had a 10 ft. spacing.  I tried both both Wolff 120 grain MPT and the new Hornady 123 A-MAX load.

The 16 inch barreled 6.5 Grendel showed:  
Wolff 120 MPT - average velocity of 2437 fps, extreme spread of 51 fps and a standard deviation of 15  
Hornady 123 A-MAX - average velocity of 2427 fps, extreme spread of 43 fps and a standard deviation of 13.  

The 18 inch barreled 6.5 Grendel gave:
Wolff 120 MPT - average velocity of 2495 fps with an extreme spread of 51 fps and a standard deviation of 18.  
Hornady 123 A-MAX average velocity of 2495 fps with an extreme spread of 44 fps and a standard deviation of 15.  

It was amazing to find that the two different brands of ammo were running so close to the same velocity out of the two different barrel length.   The extra two inches only gave approximately 58 to 68 fps difference.  Just for kicks I went to the Quick Load program and put in 18 inch barrel with 24.4 grains of H322 with a 120 grain Hornady bullet (this is a shown as a max load).  Quick Load computes this load to have a velocity of 2393 fps and 98.99% powder burn.  Entering a 12 inch barrel length into the Quick Load program with the same powder and bullet computes to a velocity of 2182 fps and 96.53 % of powder burnt.  This looks like you loose a little over 200 fps of velocity for a six inch loss of barrel.  Makes me think that I might have to build a 12 inch 6.5 Grendel SBR car gun.  

That's interesting, in all my testing Hornady has been quicker than Wolf.
Also regarding a 12 inch gun, AA 123 grain Scenar's are running at 2330 fps out of mine.
AA's 100 grain Berger load is around 2500 fps

Mikeh1911, do you mind if I ask what types of barrels you are using? I have been looking at the 16" and 18" barrel and bolt combos on Alexander Arm's website. My in the works upper will be used for paper punching and mule deer hunting. I was leaning towards the 18" barrel prior to seeing your post but now it doesn't look like the extra 2" and a 1/2 pound of weight are worth it. It is extremely unlikely I would ever shoot at game past 300 yards and I doubt I'll ever punch paper much past that distance either.

My 16 inch Grendel is a standard Wolff complete upper with 9 inch LaRue handguards.  I'm planning on cutting it down to a SBR 12 inch barrel soon.  The 18 inch is from AA.  It's a stainless steel fluted barrel.     I also have a similar 18 inch barrel on my 223/556 Krieger barreled gun that I use for 3 gun.  I like the 18 inch barrels as they seem to be a good compromise.  

If I was to do it again I would get GA Precision to build me an 18 inch 6.5 Grendel upper.  A friend of mine had them build one and it is very impressive.  GA does great work and every thing I've seen from them is excellent.  

I also don't like that AA only offer of 9/16 x 24 threaded barrels.  I like the 1/2x28 or 5/8x24 thread for the flash hiders as I use Surefire Suppressors.  The 9/16 x24 is not built by very many companies and I found this out after I received the 18 inch barrel from AA.  I should of done more research before buying one of their barrels.  

I know what you mean about the 9/16x24 threads.  I bought a Satern barrel from AA and it has the same thread.  However I did find a Smith/Vortex on Gunbroker from an AA dealer with those threads and it turned into a non issue for me since that's my preferred flash suppressor.