6.8 SPC questions

[Grassman]

I'm considering getting a 6.8 upper, mainly target and hog shooting, but I have a few questions. Know very little about this caliber.

What barrel length do you prefer 16",18" or 20"?
What are the common twist rates?
Do 223 mags work or do they require different mags?
What are ammo prices? Eventually I would get set up to reload this caliber.

Thanks....

 

[68wj]

I'm considering getting a 6.8 upper, mainly target and hog shooting, but I have a few questions. Know very little about this caliber.

What barrel length do you prefer 16",18" or 20"?
What are the common twist rates?
Do 223 mags work or do they require different mags?
What are ammo prices? Eventually I would get set up to reload this caliber.

Thanks....

It works great out of a 16" barrel. There is only negligable velocity gain going longer, but some like the balance of the longer tubes (not cartridge specific)

1/11 is the sweet spot for bullet weights and velocities. There are 1/10 makers too, and one barrel maker has a 1/7 to stabilize the 200gr subsonics.

Different mags. They look the same but the ribs are not as deep to accommodate the larger diameter case.

There is no surplus or Russian range fodder. Most of your loaded ammo is in the hunting or defense catagory until Federal's American Eagle loads solidify from the vapor they have been. PSA has Hornady Vmax for $17.99, which is okay. http://palmettostatearmory.com/inde...o-6-8mm-rem-spc-110gr-v-max-20rd/category/63/

 

[Grassman]

Thanks for the info.

 

[Dean1818]

The 6.8 is a great choice for Texas pigs

The 120g Hornady SST is my DRT bullet (Dead right there)


10ft is the furthest I have had them go


I have a Bison Armory 16" 6.8

 

[Grassman]

Ok 6.8 or 6.5 Grendal? I'm reading 6.8 is better, Grendal kinda fading away?

 

[Onewolf]

Ok 6.8 or 6.5 Grendal? I'm reading 6.8 is better.

6.8 hits harder inside 100 yds. After 100 yds the Grendel rules.

 

[68wj]

Ok 6.8 or 6.5 Grendal? I'm reading 6.8 is better, Grendal kinda fading away?

For the hunting that you mentioned, they are so close performance wise that most of the arguments over which is better are just team pep-rallies. Looking at energy on target, and velocity above the minimum expansion, it is a coin toss when trying to do apples/apples:

From Hornady's site:
Grendel 123 SST
Rifle (16" Barrel) Velocity (fps) / Energy (ft-lbs)
Muzzle: 2350/1508
100: 2189/1308
200: 2034/1129
300: 1885/971

6.8 SPC 120 SST
Test Barrel (16") Velocity (fps) / Energy (ft-lbs)
Muzzle: 2460/1612
100: 2250/1349
200: 2050/1120
300: 1862/923

Powder capacity is the case, so the 6.8's larger bore lets it get up to speed quicker while the 6.5's BC helps it maintain energy longer. Out to 300 yards from a carbine, it is a mighty dead animal.

Beyond ballistics is cartridge support. There are several rifle/upper, bolt, barrel, ammo, and magazine manufacturers for the SPC. I can not speak to G availability.

 

[dvdcrr]

I shot a big buck at a little over 100-150 yds shot landed in the ribs behind the shoulder. This made a solid thump. Buck humped up and walked slowly down a hill about a hundred feet and stood there. Never fell down. Second shot put him down. This was with a 16" carbine and factory 110 gr. ammo. Another deer shot at 50 yd. ran less than 100 feet and keeled over with a shot clean through, same rifle and ammo.

In my experience the cartridge is not "impressive" though it is adequate for most hunting. I am not convinced that it is any better than 5.56. I have never seen it do anything I could not have done with a 5.56.

I am not trying to disuade anyone from a 6.8 if you want one go for it. They are accurate. If you plan to hunt larger game than smallish deer at close range, I believe its best to go with a 20" barrel and handload 120 gr. bullets as fast as you can safely do it. From what I have seen there are substantial gains in velocity with a 20" barrel versus a 16" in this cartridge. This cartridge needs every foot per second you can give it.

 

[Gtscotty]

Dvdcrr,
Out of curiosity, what kind of bullet were you using?

 

[me26245]

6.5 Grendel

When I wanted to find a different cartridge to use in the AR platform I researched both the 6.8 SPC and the 6.5 Grendel.
Both cartridges have their perks, but after hearing how the 6.8 performed in military testing and seeing the long range attributes of the 6.5 Grendel, I decided to go with the 6.5 Grendel.
To date I've taken 4 deer with the Hornady 123 gr factory ammunition at ranges of 70 to 150 yards.
I bet if you look a little closer you'll find that it is the 6.8 SPC cartridge that is moving into obscurity not the 6.5 Grendel.

 

[Shawn Dodson]

I re-barreled a Colt AR-15A2 with a 20" 6.8 SPC-II barrel (1:11 rifling) and I'm easily achieving 2600+ fps with 110gr Sierra Pro-Hunter JSP and Hornady 110gr OTM using 26.5gr Hodgdon H332.

Good luck!

 

[strambo]

For Hog and target shooting (not long rage) also consider 300BLK. Big advantage is you just need a barrel (a complete upper would be more practical though). Same bolt, same magazines as 5.56 AR.

300BLK is just a 5.56 case necked up to .30 cal. Ballistics almost exactly like a 7.62x39.

 

[68wj]

I re-barreled a Colt AR-15A2 with a 20" 6.8 SPC-II barrel (1:11 rifling) and I'm easily achieving 2600+ fps with 110gr Sierra Pro-Hunter JSP and Hornady 110gr OTM using 26.5gr Hodgdon H332.

Good luck!

Factory Hornady VMax was giving me 2600 fps from my 18". I haven't chronied it since going to 16". I am pushing 2700 with Hornady 110 HPBT using AA2200 powder in a 16" barrel. Admittedly, this may be warm in some barrels, but my brass isn't showing it.

 

[Gtscotty]

When I had a 6.8, my load sent a 110 Accubond out of the end of an 18" barrel at 2660 fps with no problems (I actually loaded north of 2700, but the accuracy fell off). The two deer I shot with it didn't complain about the 40 fps less velocity though... come to think of it, they didn't do much of anything except drop at the shots.

As for the 6.8 SPC being on the decline, someone really should let the ammo companies know, because they are wasting lots of time and capital pumping out many different loads for the caliber, with a few more on the horizon.

 

[68wj]

As for the 6.8 SPC being on the decline, someone really should let the ammo companies know, because they are wasting lots of time and capital pumping out many different loads for the caliber, with a few more on the horizon.

Remington's 6.8 SPC Hog Hammer load is anticipated this year, but I am skeptical of what the price or performance will be. The 110 TSX is already a proven killer and could be good in this load if Remington does it right. I am more eager for the American Eagle loads, if they exist (I am on the notify list). http://www.midwayusa.com/product/89...ton-spc-115-grain-full-metal-jacket-box-of-20

 

[Grassman]

For Hog and target shooting (not long rage) also consider 300BLK. Big advantage is you just need a barrel (a complete upper would be more practical though). Same bolt, same magazines as 5.56 AR.

300BLK is just a 5.56 case necked up to .30 cal. Ballistics almost exactly like a 7.62x39.

I have a 300 also, have not shot it much, can't find ammo. I'm am gearing up to reload for the 300 black, I'm going to cut down some 223 brass.

 

[crazysccrmd]

If you have a 300blk already I wouldn't bother getting a 6.8spc also. At the relative ranges you would generally be shooting hogs, deer or paper the 300blk will be just as effective. It's basically a semi auto 30-30.

 

[cfullgraf]

300BLK is just a 5.56 case necked up to .30 cal. Ballistics almost exactly like a 7.62x39.

Actually, the 300 BLK is a 221 Remington Fireball case necked up to 30 caliber.

300 BLK cases can be made by shortening 223 Remington cases then forming the 30 caliber neck.

Yes, ballistically it is very similar to 7.62x39.

 

[Dean1818]

After reading a few posts on here, just a few thoughts:

Every one of the calibers mentioned on this thread are good calibers and have their place, much of what YOUR choice should be in YOUR personal application

Depending on what YOU want to do with the rifle, the 300BLK, 223, 6.5, OR the 6.8 may make the best choice

Questions you should ask yourself for the use of your rifle:

1) Reload or not?
2) Hunt or target?
3) Suppressed or not?
4) Game hunted small or large?
5) Range of game hunted?
6) SBR or not?
7) Already have an 223 upper you want to update, or buy a complete upper?

These questions will help YOU decide.


For me, I looked at the 300BLK, which is a great round and the 6.8.

My uses were for hunting Texas Boar at up to 250 yards and HD.
I wanted a dedicated upper, and I dont want to run suppressed.
I am a reloader.

I am a believer in the 1000 ft/lbs energy level on a decent hunting bullet
as the limiting factor for distances the I would shoot.

I looked at the best hunting bullet offered for the 300BLK, I looked at the best 6.8 bullet offered and compared the specs.

The Hornady 120SST ran over 1000ft/lbs out to 274 Yards
The best hunting bullet I could find for the 300BLK dropped below 100ft/lbs out to 130 yards. (Double the distance)

I chose the 6.8.

That was the right choice for me, and I have been happy shooting the 6.8. It has put down a few hogs.

If you hunt at 150 yards or less, the 300BLK is also a great choice. There seem to be many folks hunting with it.


The suggestion of 6.8 going away is laughable.

There are now 2 militaries in the middle east that shifted from much of their 223 to 6.8 for the extra firepower. If you look at forums such as 6.8forum, the number of new signups continue at a consistent pace.


The 6.5 DOES have superior downrange performance to both the 300BLK and 6.8 on the surface.

the barrel most chosen by a WIDE margin in AR15s seem to be the 16inch

If you go shorter, the 300BLK shines

If you go 16inch the 6.8 is has significantly more long range UMPFF (technical term ) the 6.8 is on par with the 6.5

At 24 inch barrel the 6.5 has significantly more long range UMPFF than the 6.8 and 300BLK

The problem? Not many 24inch barrels available, nor do most people want that long of a barrel in hunting and SD situations.

If you are hunting at extreme long ranges, (over 300 yards) and have a range that goes to 400 yards..... the 24inch 6.5 may be for you.

Good luck on your choice

 

[Onewolf]

The Grendel is definitely the a good choice for longer range work. I have a 20" .264 LBC (Grendel) upper. With a Hornady SST 123 it has 1000 ft-lb energy at over 400 yds and is supersonic to almost 1200 yds.

If you're staying inside 300 yds either the 6.8 or 6.5 would be good choices.

 

[Tirod]

Match the range and target to the bullet's performance. Nobody complains about the 6.5 having great long range ballistics, albeit it's not really a .308. But, it can shoot target matches like one, and that is exactly what it was made to do.

The more you shorten the barrel, the more the 6.8 delivers. It was engineered to shoot from the 14.5 military barrel and deliver 50% more power doing it compared to the 5.56. The 6.5 tends to fall off more quickly as the fat case and narrow round need barrel length to develop velocity.

The .300 BO works suppressed subsonic best of all, it's generally moving the largest bullet which makes up the difference.

Where it really applies is in hunting - few other than plains game shooters see long shots over 400 yards. The majority of game taken in America is 50-150 yards, the performance of the 6.8 matches the need with a carbine length gun that is easier to carry.

The 6.5 has it's issue with magazines, it's a tapered case like the 7.62x39, it needs to curve, but it gets fed into a straight mag well, and it's been an issue from the beginning. Magazines are reportedly problematic. But, that could also be said about any metal AR mag, and the Pmag is evidence enough it's true. However - you can't get Pmags for the 6.5 or 6.8. The cases are simply too big to accommodate polymer in the milspec mag well dimensions.

That is why the foreign contract for 6.8 carbines uses an oversized magwell and is being issued a special Pmag that fits it alone. That will eventually come to the mass market in the near future and it's going to be interesting to see how much it affects things. It will allow a longer OAL for handloaders, and both speed and accuracy will take another incremental step.

The development of the 6.8 is far from over, compared to the set recipe for 6.5 and the long history of .300 Whisper. Both of the latter are as far along as they can go. But, with a new lower and Pmags to feed from, the 6.8 has still to see it's limits.

Won't bother me to buy a new lower and use Pmags. The upper I have will just pin on. That points out the reality of a specific caliber AR - very few really swap uppers around, they generally get built for a specific purpose as a complete firearm. The notion that "all I need for the .300 is a barrel" kind of falls short considering it still needs an upper, lower, lpk, etc etc etc. All the guns need the same exact things, so far the difference is only the barrel, bolt and magazines, which aren't hard to obtain or assemble. There's no real cost savings buying parts at retail anyway.

Pick the cartridge for what you need it to do, just keep in mind trying to force it to do the others' job is why they exist - they do it better.

 

[dvdcrr]

I was informed today that Armalite will not be making any 6.8 spc uppers or rifles this year and they dont know about next. That also includes 260, 243. 7.62x39, and other calibers. Sounds like 223 and 308 will be about it fron them.

 

[Dean1818]

I wonder now that the buying surge on AR15 has slowed down, what the AR15 companies will be offering.

I think they all may pare back a bit

 

[thewilbur]

I've been experimenting with my new Rock River Coyote Carbine in 6.8 SPC Spec II, 1 in 10 rifling twist. Although I have had several failures (large groups) these work:

Hornady 110 grain V-Max Factory Ammunition, average muzzle velocity chronographed at 2534 fps, consistent 1.25" groups at 100 yards.
Sierra 115 grain Match HP, 27.5 grains H335, standard small rifle primer, Hornady brass, light "Lee Factory" crimp: average muzzle velocity chronographed at 2284 fps, 0.4" groups at 100 yards.
Sierra 115 grain Match HP, 27.4 grains (Lee Dipper 1.9) Benchmark, standard small rifle primer, Hornady brass, light "Lee Factory" crimp: average muzzle velocity chronographed at 2343 fps, 0.9" groups at 100 yards.
Nosler 110 grain white plastic tip, 28.5 grains Benchmark, standard small rifle primer, Hornady brass, light "Lee Factory" crimp in cannelure: average muzzle velocity chronographed at 2444 fps, 0.9" groups at 100 yards.
Nosler 110 grain white plastic tip, 28.0 grains H335, standard small rifle primer, Hornady brass, light "Lee Factory" crimp in cannelure: average muzzle velocity chronographed at 2366 fps, 0.9" groups at 100 yards.

 

[Float Pilot]

There is only negligable velocity gain going longer,

That is not really true.

The velocity gain per inch is about the same as any other non-magnum cartridge , from 16 inches out to a 24 inch barrel. About 25 to 32 feet per second in velocity gained for every extra inch of barrel length.
It seems that the heavier bullets like a longer barrel



6.8mm SPC 16 to 24 inch barrel conversion velocity and accuracy test.

16 inch barrel, Stag factory 1 in 10 twist SPC-II chamber

24 inch barrel, Black Hole Weaponry, 1 in 11 twist, SPEC II.

Fired at @ 50 degrees F. Alt 350 feet.

NOTE**** These are not the best velocity loads for the 24 inch barreled rifle. They just happened to be loads that I did not mind shooting that particular day.


90 grain Sierra JHP
28.8 grains H-4198
SSA Brass, CCI-BR-4 primer
COL- 2.200 inch, Lee Crimp
16 inch = 2,908 fps and 0.40 inch group
24 inch = 3,110 fps and 0.75 inch group


90gr Sierra HP
31.5gr AA-2200
2.219 in COL
16 inch Vel= 3,020 fps and 0.75 inch group
24 inch Vel= 3,265 fps and a 0.50 inch group

95gr Barnes TTSX
31.0gr AA-2200
2.230 COL
16 inch Vel= 3,060 fps
24 inch Vel= 3,270 fps and a 1.0 inch group


100 grain Bulk mystery SP.
29.7 grains H-Benchmark
SSA Brass, Fed 205 primer
COL=2.255 inch, Lee Crimp
16 inch = 2,650 fps … Large group
24 inch = 2,750 fps--- 0.50 inch group, no flyers.

100 grain Remington SP
31.5 grains AA-2230
SSA brass, CCI-400
COL-2.225”, Lee Crimp
16 inch = 2,580 fps Group over 2 inches
24 inch = 2,765 fps… 0.75 inch group

110gr Nosler Accubond
29.0gr AA-2200
2.260 col
16 inch Vel= 2,750 fps and a 1.1 inch group
24 inch Vel= 3,020 fps and a 1.4 inch group

110 grain Nosler Accubond
29.0 grains H-322
SSA Brass, CCI-BR-4
COL-2.265” Lee Crimp
16 inch = 2,554 fps and 1.0 inch group
24 inch = 2,730 fps and one ragged hole at 100 yards.

110 grain Nosler Accubond
25.8 grains AA-1680
SSA Brass, BR-4 primer
COL-2.250”, Lee Crimp
16 inch = 2,500 fps and 1.5 in group
24 inch = 2,770 fps and 0.50 inch group average



110 grain Sierra Pro-Hunter
25.8 grains AA-1680
SSA Brass, BR-4 primer
COL-2.250”, Lee Crimp
16 inch = 2,470 fps and 2.5 in group
24 inch = 2,608 fps and 1.0 inch group average

110 grain Sierra Pro-Hunter SP
30.8 grains AA-2230
SSA Brass, CCI-400
COL 2,255”, Lee Crimp
16 inch = 2,550 fps,,1.0 inch group
24 inch = 2,730 fps ..0.75 inch group


110 grain Hornady JHP.
30.8 grains, AA-2230
SSA brass, CCI-400
COL=2.255, Lee crimp.
16 inch = 2,530 fps….. 2.5 inch group
24 inch = 2,760 fps----1.1 inch group

110 grain Barnes Triple Shock
30.5 grains AA-2230
SSA Brass, CCI-400 primer,
COL-2.237, Lee Crimp
16 inch = 2,550 fps 1.5 inch group
24 inch = 2,820 fps 0.80 inch group

110 grain Hornady Factory Ammo.
110 grain BTHP
16 inch = 2,455 fps
24 inch = 2,699 fps 1.5 inch group

110 grain Ballistic tip type load factory
16 inch = 2,506 fps
24 inch = 2,790 fps 1.0 inch group

120gr Hornady SST BC=.400
28.5gr AA-2200,
CCI BR-4 primer
2.252 col
16 inch vel= 2,545 fps and a 1.5 inch group
24 inch Vel= 2,820 fps and a 0.50 inch group

130 grain Sierra S.P flat base
27.0 grains H-Benchmark
SSA brass, Rem 7.5 primer
COL= 2.55 inch, Lee crimp
16 inch = 2,220 fps…1.0 inch group
24 inch = 2,480 fps and 1.0 inch group
No pressure signs.

150gr Speer Soft Point Flat Base
25.0gr AA-2200
2.280 col
16 inch Vel= 2,020 fps and a 0.80 inch group
24 inch Vel= 2,360 fps and a CLOVERLEAF HOLE