Christensen Arms

Predator Masters using UBB.threads ™ Infopop Corporation.
PM Gear Moon & Weather

Welcome to the Predator Masters Forums
Be sure to visit the main Predator Master website at





PM Gear
PM Gear
PM Gear
The Official Predator Masters Search Engine
Search Predator Masters

Topic Options
#1285419 - 05/03/09 11:58 AM 6.8 spc ???
Aznative Offline
Die Hard Member

Registered: 06/11/02
Posts: 771
Loc: Phx
I have a question about the 6.8 spc. Wikipedia says, "In recent developments (the period 2004-2008) the performance of the 6.8SPC has been increased by approximately 200 ft/s by the work of one ammo manufacturer and a few custom rifle builders using the correct chamber and barrel specifications."

Here is the link to the above quote:
http://en.wikipedia.org/wiki/6.8_mm_Remington_SPC

Unfortunately wikipedia does not tell us what these improves are. So my queston is this: What chamber specs and barrel specs are used to achieve these velocity improvements. What are the improvements in ammo and are they availbable to the reloader?

Thanks in advance
_________________________
Madoff's ponzi scheme is small potatoes compared to the Social Security Administartion;s scheme

Top
#1285420 - 05/03/09 01:37 PM Re: 6.8 spc ??? [Re: Aznative]
txagyotebuster Offline
Seasoned Member

Registered: 10/19/05
Posts: 470
Loc: rosebud, tx
the new improvements include slowing the twist rate from 1:9 or 1:9.5 to 1:10 or 1:11 or on custom guns even 1:12.

the chamber size has been slightly modified as well. the new SPC II or on some custom guns the DMR chamber. these newer chambers are slightly longer in the throat (similar to the differences in a standard .223 chamber, 5.56 chamber, and a 5.56 wylde chamber).

these modifications have greatly reduced pressures allowing for greater velocity to be achieved.


this is something that has drawn me to ordering a 6.8.

this little cartridge still does not have the horsepower or a WSSM AR, but the 6.8 was designed to be shot in short barrels (16") where as the WSSM's need 20+ in barrels to achieve maximum potential.

for what i want this rifle to do the 6.8 fit the bill better than a WSSM

Top
#1285421 - 05/03/09 04:02 PM Re: 6.8 spc ??? [Re: txagyotebuster]
gary paugh Offline
Die Hard Member II

Registered: 12/20/03
Posts: 1928
Loc: portland oregon
Mine has the type 1 chamber and a 1-10 twist and the coyotes dont seem to notice the lack in velocity
_________________________
Mark Twain described the coyote as
“ a living, breathing allegory
of Want. He is always hungry. He
is always poor, out of luck and friendless.
The meanest creatures despise
him and even the flea would desert him
for a velocipede.” .

Top
#1285422 - 05/03/09 04:47 PM Re: 6.8 spc ??? [Re: gary paugh]
Aznative Offline
Die Hard Member

Registered: 06/11/02
Posts: 771
Loc: Phx
I read an article in the June Guns and Ammo about the 6.8 spc, and what go my interest up was a ballistic comparison chart for the 6.8SPC. They show this cartridge hitting a muzzle velocity of 2,800FPS. The performance of this cartridge is just below a 257 Roberts.

I found and read this article:
http://demigodllc.com/articles/6.8-mm-sp...ms-carbine/?p=1

This article shows it going 2650. It may take a little longer for the ammunition and gun makers to catch up with this promising little cartridge. It does look to be a great small to medium game cartridge.
_________________________
Madoff's ponzi scheme is small potatoes compared to the Social Security Administartion;s scheme

Top
#1285423 - 05/03/09 06:20 PM Re: 6.8 spc ??? [Re: Aznative]
deerassassin Offline
Seasoned Member

Registered: 03/25/09
Posts: 396
Loc: Fairfield, Iowa
Don't mean to jack your thread but why didn't they use a 6.5(.264) instead of 6.8(.277). The ballistics are better. Are the 6.5s to long for AR15 action? There is also the 6.5 MPC(multi purpose cartridge).


Edited by deerassassin (05/03/09 06:21 PM)

Top
#1285424 - 05/03/09 06:34 PM Re: 6.8 spc ??? [Re: deerassassin]
Aznative Offline
Die Hard Member

Registered: 06/11/02
Posts: 771
Loc: Phx
This is from the article in the above link:

"Once the case dimensions were tweaked to fit and work in M4-compatible magazines, the project team quickly turned their attention to bore size. Derivative wildcats from 5.56mm to up 7.62mm diameter shooting bullets from 90 to 140 grains were subjected to a battery of tests, and a sweet spot emerged. The 6.5mm bullets showed the best accuracy and the 7mm bullets were the most destructive, but the 0.277-inch bullets showed almost the same accuracy and trajectory as the 6.5mm and almost the terminal performance of the 7mm. When necked down to 0.277-inch and shooting 115-grain bullets, it provided the best combination of combat accuracy, reliability and terminal performance for up to 500 meter engagements. This cartridge was deemed 6.8 Remington Special Purpose Cartridge (SPC), because 0.277 inch is 6.8mm in metric and .30 Remington provided the parent case. "
_________________________
Madoff's ponzi scheme is small potatoes compared to the Social Security Administartion;s scheme

Top
#1285425 - 05/03/09 06:54 PM Re: 6.8 spc ??? [Re: Aznative]
txagyotebuster Offline
Seasoned Member

Registered: 10/19/05
Posts: 470
Loc: rosebud, tx
if you are interseted in this caliber go over to the 68forums everything you want to know about he 6.8 is there. those guys are very helpful and have done alot for the improved ballistics of this cartridge.

Top



Moderator:  Infidel 762 

© Predator Masters™, All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.