Pros and Cons of a 6.8 Rem SPC vs 5.56?

[Veritas_223]

I got an Ameetec lower marked 6.8 Rem SPC today. It started me thinking, what are the pros and cons of 6.8? Is 6.8 Ammo available? Are 10 round mags for 6.8 around for a fix mag build? I assume i will need a 6.8 Complete Upper, what are the brands? RockRiver does not seem to have a 6.8.

Thanks!

V

[Stanze]

Copied and Pasted from: http://accuracysystemsinc.com/ruger_mini_prices.html

*begin copy and paste*

The 6.8mm Remington SPC

By Chuck Hawks



The inadequacies of the 5.56mm NATO as a service rifle cartridge are well documented and have inspired many suggestions regarding possible replacements (some on this web site). Apparently someone in the U.S. Special Operations Command also realized the need for a more potent round and initiated work on a new cartridge designed to work in the M16 action.

The new .270 caliber (6.8mm) cartridge is the result of at least a two year cooperative effort between Special Operations, the Army Marksmanship Unit, and Remington. Various calibers from .22 to .30 were tested before settling on a standard .277" diameter bullet, the same bullet diameter made famous in the .270 Winchester.

Remington is offering four 6.8mm SPC factory loads, all with 115 grain bullets. These include two target loads, a Core-Lokt Ultra hunting load, and a Metal Case military-type load. No varmint load is included. The four factory loads all have a muzzle velocity (MV) of 2800 fps and a muzzle energy (ME) of 2002 ft. lbs. from a 24" test barrel. At 100 yards the metal case bullet (BC .325) has a remaining velocity of 2523 fps and energy of 1625 ft. lbs. At 200 yards the velocity is 2262 fps and the energy 1307 ft. lbs. And at 300 yards the velocity is 2017 fps and the remaining energy 1039 ft. lbs. These figures are taken from Remington's 2004 catalog.

The trajectory of the metal case bullet looks like this: +1.2" at 50 yards, +2.7" at 100 yards, + 2.8" at 150 yards, +1.4" at 200 yards, -3" at 267 yards, and -6.6" at 300 yards. The maximum point blank range (+/- 3") is thus 267 yards. These figures are computed for a rifle with a telescopic sight mounted 1.5" over the bore. This, just like the Army claimed, is similar to the trajectory of the .308 with a 150 grain bullet.

The lighter weight .277" varmint and hunting bullets will presumably be the most popular choices in the 6.8mm SPC, and the latter are not thick on the ground. Suggested examples include the 90 grain Speer HP varmint bullet, 100 grain Barnes X-Bullet, 115 grain Sierra HPBT, 115 grain Remington Core-Lokt Ultra, and 120 grain Barnes X-Bullet.

Fast to medium burning rifle powders such as RL-7, IMR 4198, IMR 3031, IMR 4895, H4198, H322, H335, and Benchmark are indicated in the 6.8mm SPC. The MAP of the 6.8mm SPC appears to be about 55,000 PSI.

Here is some reloading data from the Hodgdon Powder Company:

Starting Load - 90 grain Speer HP bullet, 26.0 grains of H4198 powder, MV 2810 fps, 47,700 PSI.
Maximum Load - 90 grain Speer HP bullet, 28.6 grains of H4198 powder, MV 3012 fps, 54,000 PSI.

Starting Load - 100 grain Barnes X-Bullet, 27.0 grains of H322 powder, MV 2502 fps, 37,700 PSI.
Maximum Load - 100 grain Barnes X-Bullet, 30.0 grains of H322 powder, MV 2803 fps, 52,300 PSI.

Starting Load - 115 grain Sierra HPBT bullet, 26.0 grains of H322 powder, MV 2421 fps, 43,500 PSI.
Maximum Load - 115 grain Sierra HPBT bullet, 28.2 grains of H322 powder, MV 2608 fps, 53,300 PSI.

These loads were chronographed in a 24" test barrel using Remington cases and Remington 9 1/2 primers.

Note: A full length article about the 6.8mm SPC can be found on the Rifle Cartridge Page.

[Hanniballs]

The only diff is the stamping. Its exactly the same lower.

[double_action]

Stanze answered part of you question(s)

My contibution: yes 10 round mags are available, but expensive. I know Barrett makes some that are (I think) $40. You can also modify 5.56 mags. Google got me these really quick . . . I'm sure you could find cheaper mags, these are a pretty penney . . .

http://www.pri-mounts.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PRI&Product_Code=05_6807m&Category_Code=6_8_MM

http://www.gunaccessories.com/AR15-M16Parts/6-8mmSPCPartsandAccess.asp

Some one else chime in on uppers . . . .

[double_action]

guess I missed that thread.

Thanks for the correction Ted

[highlandr]

6.8 Spc

I just picked up my Ameetec this morning, and was pleasantly surprised that it also was stamped with CAL 6.8 SPC, since I was planning on building one with this receiver!

If you can, pick up a copy of "Book of the AR-15" magazine by Guns&Ammo; there is an excellent article by David Fortier on 6.5 Grendel and 6.8 SPC caliber options. It may even be available online--I haven't had time to check yet.
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