6.8 SPC Inherent Accruacy

[Dobe]

I have read and heard, as most have, that certain cartridges are inherently accurate, and others are not. I just read an article in the latest American Rifleman, where the author states that the 6.8 SPC is not an inherently accurate round.

I am of the age that I remember such claims of other cartridges such as the 9mm Parabellum. I can remember reading articles, where the authors would claim that the 9mm's lack of accuracy was linked to the tapered case, etc. Apparently, this is not the case.

I can only assume there is not a standard for this (SPC II, 1:11 twist)
cartridge. At least not one that is widely accepted, and used.

I'm just wondering if any of you have consistent groups in the 1 moa range with the 6.8 SPC. If so, what type of platform, i.e. bolt, AR, etc.

 

[okiewita40]

Go check out the 68forums. There is a link there for the american rifleman article. another few entries is another link to a different article that is the polar oppisite of the one in american rifleman.

Most everyone that has a 6.8 with the updated spec's report moa or better with most of the loads. Although the tighter twist seems to shoot the v-max rounds better. And the 6.8 will not drop to the ground at 300 yards.

 

[longdayjake]

Let me just put it this way. The 6.8 SPC is not inherently more accurate than any other cartridge out there. The platform that it is shot from is what determines that accuracy. If you shoot a cheap 6.8 you can expect cheap results. If you shoot top of the line AR in 6.8 you can expect top of the line results. Everyone pretty much agrees that the .223 is inherently accurate, unless you shoot it from a mini14. The same holds true with the 6.8.

One thing that affects the accuracy of the 6.8 is the fact that those short fat bullets get blown around by the wind pretty good. On a perfect day you shouldn't have too hard a time getting great results from a great rifle, but on a windy day the 6.8 will be blown around pretty bad the further out you try to shoot. Remember, it shoots really fast at the muzzle but the bullets slow down relatively quick. So, depending on the rifle and the conditions any particular 6.8 could be a crappy shooter and then the next day it could be a one hole tack driver.

 

[R.W.Dale]

Longday pretty much summed it up. My personal view is that any time I read someone pontificating about a cartridge's Inherent Accrua........ ....................................................................................that's where I stop paying attention to what they have to add. I even once built a bench gun in 7.62x39 just to prove this point.

One thing that affects the accuracy of the 6.8 is the fact that those short fat bullets get blown around by the wind pretty good. On a perfect day you shouldn't have too hard a time getting great results from a great rifle, but on a windy day the 6.8 will be blown around pretty bad the further out you try to shoot. Remember, it shoots really fast at the muzzle but the bullets slow down relatively quick. So, depending on the rifle and the conditions any particular 6.8 could be a crappy shooter and then the next day it could be a one hole tack driver.

True but I wouldn't go so far as to say that's a direct function of the cartridge itself but rather what you're using to shoot it from and what bullets you choose. You could build a 6.8 that would shoot any .277" berger VLD you wanted. Granted the velocity would be limited.

 

[68wj]

The interesting part of that article is the side bar by Bill Wilson. Though they are both writing about the came cartridge, it sounds like they are discussing two different rounds.

 

[Dobe]

My feelings on "inherently accurate" cartridges is that if the .45 ACP (which has the BC of a watermelon) can be made accurate, then just about any other cartridge can be also. It's a matter of finding the correct bullet launcher.

I was looking for some first hand experience from some of the 6.8 shooters.

 

[longdayjake]

I own and shoot AR's in 5.56, 6.8 spcII, and 6.5 grendel. The 6.8 is accurate enough to keep up with the others. Like I said before, it is the gun and the load that is accurate not the particular casing the bullet is seated into.

 

[Welding Rod]

Rock River claims 1 MOA for their 6.8 guns.

I have no experience with the 6.8, but my experience with Rock River is that their guns don't have trouble meeting their accuracy claims.

 

[68wj]

I'm just wondering if any of you have consistent groups in the 1 moa range with the 6.8 SPC. If so, what type of platform, i.e. bolt, AR, etc.

Yes. I have not shot paper beyond 100 yds with it, but the few factory loads and all handloads of various bullets are MOA or less out of my 18" barreled AR.

 

[Float Pilot]

There have been some real odd things coming out of American Rifleman over the past couple years. "Although it is not nearly as bad as what has happend to G&A"
I guess that is what happens when all the good investigative shooters / writers die off from old age.

It is the platform, barrel and load...that makes a cartridge accurate.

Here is a group from a 16 inch Stag factory rifle. 1 in 10 twist SPEC II chamber.

NOTE*** This group was obtained after I modified the feed ramp to an M4 style and polished the heck out of it.

Here are some samples of my load experiments.

Bullet: 100 grain Sierra sp. flat base
Powder: 30.0 grains, H-322
Primer: CCI-400 small rifle, hand seated
Brass: SSA
COL: 2.240 inch med roll crimp.
Velocity average: 2,556 fps 9 fps ES
0.35 inch group with last shot flyer to 0.80 inch. Flat Primers

Bullet: 110 grain Nosler Accubond Boat-Tail
Powder: 29.0 grains H-322
Primer: Federal 205 , Standard Small Rifle, hand seated
Brass: SSA
COL: 2.260 inch Lee Factory Crimp
Velocity average: 2,483 fps 33 fps ES
0.5 inch group, with flyer to 1.5in NO Pressure signs. Some firing pin dragging on primer face

Bullet: 110 grain Sierra Pro-Hunter SP, flat base
Powder: 31.0 grains AA-2230
Primer: CCI-BR-4 Small Rifle hand seated
Brass: SSA
COL: 2.255 inch Lee Factory Crimp
Velocity average: Chronograph Failed at 8 below
0.28 inch group, Some moderate Pressure signs
Loads very well, Clean Brass



Bullet: 130 grain SIERRA, flat base, spitzer SP
Powder: 31.0 grains, WW-748
Primer: CCI-400 small rifle, hand seated
Brass: SSA
COL: 2.265 inch Lee Crimp.
Velocity average: 2,220 fps 39 fps ES
0.70 inch group Flat primers


Bullet: 130 grain SIERRA, flat base, spitzer SP
Powder: 27.0 grains Hodgden Benchmark
Primer: CCI-41 Military Small Rifle hand seated
Brass: SSA virgin
COL: 2.260 inch Lee Factory Crimp
Velocity average: 2,208 fps at +5 degrees 10 fps ES
0.68 inch group, no pressure signs