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Subject: The Caliber Conflict
James Dunnigan    1/20/2005 10:38:21 PM

The new 6.8mm rifle round developed for SOCOM (Special Operations Command), will be available commercially later this year as the 6.8mm Remington SPC (Special Purpose Cartridge). The manufacturer says the round won’t be available to the public until the middle of the year, because of the need to produce sufficient quantities of the round for military contracts. There have been some problems in manufacturing the 6.8mm SPC. Remington began work on the new round in 2002. It used the case from the old Remington .30-.30 (which was not a true .30-.30, as it was rimless.) SOCOM has been testing the 6.8mm round in M-16s and M-4s modified to accommodate it. The 6.8mm round is more accurate at longer ranges and has more hitting power than the 5.56mm round the M-16 was originally designed for. Out to about 600 meters, the 6.8mm round has about the same impact as the heavier 7.62mm round used in sniper rifles and medium machine-guns. 

During the 1930s, the Germans studied their World War I experience and concluded that a less powerful and lighter rifle round would be more effective. This resulted in research on a smaller 7mm round, but with World War II fast approaching, this effort eventually produced a shortened regular  (7.92mm) rifle round. During that war, the Germans developed the first modern assault rifle, the SG-44. This weapon looked a lot like the AK-47, and that was no accident. The SG-44, like the AK-47, used a shortened rifle cartridge that was developed before the war (7.92mm for the Germans, 7.62mm for the Russians, which is still used in the AK-47). This gave the infantryman an automatic weapon that could still fire fairly accurate shots at targets 100-200 meters away. The SG-44, and the AK-47, had about the same stopping power as the 6.8mm SPC at those shorter ranges. What a coincidence. The AK-47 didn't have the accuracy of higher powered bullets, but the Russians didn't see this as a problem, because most troops using it had little marksmanship training. If they had to kill someone, they could fire at full auto. The U.S. M-16, and its high speed 5.56mm round, was more accurate than the AK-47 when firing individual shots at shorter ranges. But the wounding power of the 5.56mm (.22 caliber) bullet fell off rapidly at ranges over a hundred meters. The American military, and especially SOCOM, train their troops to fire individual shots, and do it with great accuracy at any range. A number of new rifle sights have made even easier to do, and makes first round hits at longer ranges easier to make. This made the longer range shortcomings of the 5.56mm round more obvious.

SOCOM has been using the 6.8mm round in Iraq and Afghanistan, and the users like it. But there is resistance from senior (non-SOCOM) generals to any consideration for replacing the 5.56mm round with the 6.8mm. To further complicate matters, there’s a new 6.5mm “Grendel” round being tested as well, and some troops prefer it to the 6.8mm SPC. This is because the 6.5mm round is more accurate than the 6.8mm one at ranges beyond 500 meters. At the moment, no decision has been made about any replacement for the 5.56mm round.

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CJH    RE:The Caliber Conflict   1/22/2005 7:50:18 PM
I read an internet article which characterized the 6.8 SPC case as either a cut down or shortened 30 Remington case. My Hornady 3RD Edition handloading manual lists only a 30-30 Winchester. The manual has a 35 Remington (good lever action carbine round) and I see references on Google to 30 Remington one of which characterizes it as obsolete. Also I note the 30-30 Winchester case is a rimmed case and the same Google reference site says the 30 Remington is a rimless version of the 30-30. They also say the 6.8 SPC has the same performance as the 30-30. I run NRA High Power matches and the AR-15 is the current favorite service rifle pattern. Not for my reduced range matches but for 600 yard match stages and for long range high power there might be some takers for the 6.8 SPC although the 6.5 mm competitor might be more popular.
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MajB    RE:The Caliber Conflict   3/15/2005 5:22:12 AM
Good article...I am one that feels the 6.5 Grendel would be a better option. The ballistics comparison between the 6.5 Grendel and 6.8 SPC when using the same weight bullets 100 to 115 gr show no significant differences. (within a few FPS) The advantage the 6.5 Grendel has is the shorter case (designed with higher powder capacity) can use 70gr to 150gr bullets without significantly effecting powder capacity. When you try to load heavier bullets in the 6.8 SPC (and fit in the AR platform) you use more powder space and reduce the velocity greatly. Due to better cartridge case design the 6.5 Grendel is much more can load light 70-115gr bullets for great stopping power in combat at short ranges or you can load heavier 120gr+ bullets for longer range shooting and penetrating battlefield objects. With the 144gr Lapua bullet loaded the 6.5 Grendel performs better than the 7.62 NATO at ranges beyond 500meters. The 6.8 SPC does not have this advantage. The 144gr match bullet has also pentrated 1.575" armored glass panels by VistaSteel when tested last year. Overall the 6.5 Grendel offers versatility we need: Long and short range performance, improves on 5.56mm at all ranges, improves on 7.62mm at long range, more accurate than 6.8 SPC, less wind effect than all others mentioned, less bullet drop than all other mentioned. I think the brass is balking at the 6.8 SPC because it hasn't had a real comparison to alternatives such as the 6.5 Grendel.
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