Why 6.8spc?
 

Well I started looking into 6.8spc when thinking about doing a new AR build but I have recently decided to go with a 300 fireball instead. Looking into loads and such I do not see why 6.8 spc exists. When looking at a "perfect" setup for the military why in gods name did they not think to mess with the 300 fireball (whisper) platform. I dont see anything that 6.8 does better than 5.56 that 300 does not do and better. 6.8 only has one bullet weight where with 300 you can go supersonic or subsonic. Finally, why would the military build something that needs a new upper when you can do the job better with just a barrel swap.

I am just not getting it, is there any reason to go with a 6.8?

I too have looked into the 6.8SPC and wondered why the 6.5 Grendel didn't win that contest. Both of these 6's give more energy at shorter ranges and the 6.5 gives a lot better terminal ballistics at ranges over 500 yards.

Both of these cartridges detriment was making ammo heavier, or the lack of use is probably the same reason why our military isn't using dragon skin armour.

Politics.

I have looked at the 300 Whisper and can't justify its existance over the 7.62x39. With C-Products making reliable mags, it makes for cheap practice ammo, a higher velocity than the 300 Whisper and it too can be loaded down to sub-sonic velocities as well.

My personal choice was the 6x45. Again just a barrelswap.
6mm projectiles from 40 to 107grains and velocities higher than the same bullet weight in the parent 223 cartridge.

For longer range work I chose the 243WSSM.

What is everyone elses thoughts?

The 6,5 Grendel breaks bolts when loaded to pressures that give you the stated ballistics.


You are absolutly correct... it is about the number of rounds/lbs.



The C-Products mags are not that reliable. I do agree that the 7.62x39 is an intresting cartridge, just as the 30 Rem. is an intresting cartridge.

If the 6.5 Grendel or the 6.8 SPC were going to break into military use the had to be able to use the same bolt and mags! (By the way shooting a Beta-C mag is very cool). Also if you want to see what really killed off the 6.5 Grendel or the 6.8 SPC military asperations look at the Sierra or Hornaday catalogue and look at the new .22 caliber heavy weights:

77 gr HPBT also called the open tip match bullet
80 gr HPBT
90 gr HPBT

One might have some problems with the 80 and 90 pills... but I think you get my point. These bullets shoot nearly as flat and hit as hard as the ~90 gr bullets out of the 6.5 Grendel or the 6.8 SPC.

320pf

YEs it probably wouldnt take much R&D to figure out a way to make 90grn 5.56 feed reliably. At least not the $$$ the army would spend replacing uppers.

reinforcements
 

I do not mean to direct people away from this site, but these is quite a discussion going on at AR25.com. It would be nice to get some more 300 whisper views represented there. The group there is VERY 6.8 SPC focused.

Here is the link
(AR-15 » AR Variants » Why 6.8 when 300 whisper is available.)

http://www.ar15.com/forums/topic.htm...f=121&t=351653

By the way kogashuko started this by asking the same question on the ar15.com site

320pf

old post but still very UNTRUE on several levels. the 6.5 grendel is NOT breaking bolts.BUT IT IS still in operation in MANY places of action in our armed forces hands ( Afghanistan is seeing how effective it is vaporizing camel jockeys at 1000 yards as we speak!) now try getting the 80 and 90 grain bullets out of a .223 to shoot 600+ while still staying SUPERSONIC! do the math, it wont happen with them. IT WILL with the grendel.

WOW, I didn't realize that the Grendel was in Afghanistan. What's the NSN for the the ammo and rifles? :bangin:

Kevin

Run the 6.8 brass through a 30 Herret die and you get something considerably more useful when coupled with the right barrel twist.:wink:

Too easy. It happens all the time with 77 and 80 gn bullets.

Afghanistan is the last place I would want to be with an oddball caliber like the Grendel. Getting ammo and spare parts could prove tough. When I was there it isnt like walking down the street and picking them up at the 7-11. If you want 9x19, 5.56 or 7.62 it is easy. 300 WM, 338 Lapua and 50 is hard enough.

Did the Math.


Name: 5.56
Ballistic Coeff: 0.362
Bullet Weight: 77
Velocity: 2650
Target Distance: 200
Scope Height: 1.500
Temperature: 70
Altitude: 1000

Ballistic Data
~~~~~~~~~~~~~~~
Range Elevation Velocity
0 yds -1.50 in 2650 fps
25 yds -0.07 in 2592 fps
50 yds 1.04 in 2534 fps
75 yds 1.81 in 2478 fps
100 yds 2.24 in 2422 fps
125 yds 2.29 in 2366 fps
150 yds 1.95 in 2312 fps
175 yds 1.19 in 2258 fps
200 yds -0.00 in 2205 fps
225 yds -1.63 in 2152 fps
250 yds -3.73 in 2101 fps
275 yds -6.30 in 2050 fps
300 yds -9.46 in 2000 fps
325 yds -12.96 in 1949 fps
350 yds -17.10 in 1900 fps
375 yds -21.90 in 1852 fps
400 yds -27.38 in 1805 fps
425 yds -33.57 in 1759 fps
450 yds -40.49 in 1714 fps
475 yds -48.14 in 1670 fps
500 yds -56.55 in 1626 fps
525 yds -65.73 in 1584 fps
550 yds -75.68 in 1542 fps
575 yds -86.42 in 1501 fps
600 yds -98.44 in 1462 fps
625 yds -111.41 in 1424 fps
650 yds -125.57 in 1387 fps
675 yds -140.94 in 1352 fps
700 yds -157.49 in 1318 fps
725 yds -175.23 in 1286 fps
750 yds -194.15 in 1254 fps
775 yds -214.72 in 1225 fps
800 yds -236.79 in 1197 fps

About 900 yards for 5.56mm.

When J.D. Jones designed the 300 Whisper, the intention was an efficient cartridge with a heavy bullet for close range sniper work. The original intent was to use 200+ grain bullets for their terminal energy out to around 200 yards or so, using a suppressor to prevent giving away the sniper's position. The intent was also for the cartridge to work in the existing AR-type rifle. The added 8" twist rate helps to stabilize the long, heavy bullets.

However, the 300 Whisper was not intended for use as a "long range" caliber. The 308 or 7.62x54 fills that niche, and lately the 50 BMG. I think the 6.8 was more or less one company's failed attempt to sway the military to use a larger, heavier cartridge that falls somewhere between the .223 and the .308. Happens all the time, politics you know. After all it was mostly politics that swapped us from the M-14 to the M-16. The M-14, as fine a weapon as it was, was only issued for a few years, while the rest of the world used (and still uses) FN-FAL's chambered in 7.62x54.

There is nothing wrong with the 6.8 SPC, as a matter of fact it's a fine cartridge. It's capable of astonishing accuracy at much further ranges than most of us are capable of shooting. I don't particularly want one or need one, that's why I chose to build my AR in 300 Whisper. Mostly because of bullet selection, just as you stated in the first place, not for any sort of long distance shooting. I also don't plan to pack a couple of hundred rounds of ammo into the woods with me when I go hunting with it.

Obviously most of the commentors here have not actually used the 6.8, especially to kill stuff................

We shoot hundreds of animals a year on the ranch in TX, mostly with AR platform weapons chambered in (listed in order of effectiveness):

.30 Rem AR
6.8 SPC II
7.62x40
300 Whisper/Blackout
5.56

After thousands of rounds down range and over 100 hog/deer kills with it I can assure you the 6.8 SPC is the best and most effective all around cartridge for hunting that will fit in the AR-15 platform. It's killing power is vastly superior to the 5.56 with any bullet including the very effective Barnes 62gr TSX. It gives up a little to the .30RAR at under 150yds, but it better all around with it's flatter trajectory, especially when using caliber specific bullets like the Barnes 95gr TTSX and Nosler 100gr Accubond.

I like my 300 Blackouts and especailly my 7.62x40, but they are 150yd cartridges in the real world of hunting.

If you want to learn more go to the 68forum ................

BTY, we have NO function issues with C-Prod or PRI 6.8 mags !!!! Our 6.8s are just as reliable as our 5.56 guns.

I'll agree, I love my 300 Whisper, but it does not have the effective range of the 6.8. Here in Mississippi however, the 300 Whisper is a very good choice. I don't personally own a 6.8, but like I said, there certainly 'aint nuthin' wrong with it! The 6.8 would be a good choice also, I just like fooling around with the 300 Whisper!

Yep, if someone's looking for "range" as well as terminal energy, there are much better choices than the 300 Whisper like the 6.8, 6.5 Grendel, and now the 300 Olympic SSW, just to name a couple.

Ha!, I am sitting here with 18 stitches in my arm and not able to run my new mill or reload ammo, and was thinging about building a 30HRT off a howa or rem when I saw this.

I agree, unless you hunt on a power line or have a corn field, here in Ms. "especially the coast where I am" the whisper is the perfect choice.

The 7.62x39 is one of my favorite cartridges. However, it's just not as versatile as the 300 Whisper. The relatively extreme taper of the case body limits the versatility of the cartridge. It works well for reliability in the original rifles that it was designed for, the SKS and AK47, but you'll notice that the factory offerings are mostly limited to the 2 bullet weights, and those are .310 - .311 bore.

Since I am a handloader, I ordered a custom barrel in 7.62x39 with a .308 bore. I figgured that the .308 bore would open up a whole world of options for a very common cartridge. I was sorta right! However, most loads that would be considered safe in a very similar cartridge as far as case capacity, the 30 Herret, will go overpressure in the 7.62x39. The tapered case causes a higher rearward thrust, and in my barrel, resulted in the action getting stuck and hard to open.

The 300 Whisper, in comparison, has a relatively straight wall case below the neck. This allows the bullets to be pushed to higher velocities than would be expected, and allows for the use of very heavy bullets, both in subsonic as well as supersonic loads.

If you use you imagination....take a 7.62x39 as a parent case, expand the case walls out almost straight, and chamber it in a 6.5 diameter bore and Viola!, you get a 6.5 Grendel. Take the same thing and make it a .308 bore and you get a 30 AR (sorta), etc. and so on....

Using an AR sized rifle for four legged critters like boar, give me a 6.8

Using an AR sized rifle for two legged critters that are also hunting you, give me a 5.56

I like them all.

I have 5.56s, 6.8s and a 300/221 with a tp555 bbl.

I whole heartedly agree with the analysis that the whisper-like cartridges are intended for ranges of 150 yards or so, and that the 6.8 is a much better hunting cartridge than the 5.56.

When I decided to go with the 6.8 versus the Grendel ... it was because I have a nice Mauser in .264 Win Mag and seldom hunt beyond 300 yards with an AR. Was also concerned abt the potential of bolt failures with the Grendel (which HAVE been reported!).