The 6.8SPC is a better terminal cartridge, sure. Is it even 20% better than 5.56? I don't know, but that's about what my un-educated bubba-guestimate would be form what little test data I have seen.
Is it even worth trading away 5 rounds of 5.56 (30 round vs 25 round mags) ? I dunno, but I'm not ready to jump up and say "oh yeah!"
One thing is for sure, it does not at this time seem equal to the 7.62x51 even in FMJ. And the 7.62 is no silver bullet.
Artherd, the 115 grain 6.8mm bullet appears to have a similar ballistic coefficient to the 150 grain 7.62mm, and is launched at a similar velocity in barrels of comparable length. So with similar bullet types it should have about 75% of the effectiveness of the 7.62mm. However, the US M80 7.62mm bullet doesn't fragment when it tumbles, whereas the 6.8mm reportedly fragments at least out to 300m, significantly enhancing the wounding potential.
I have not yet seen a full range of comparative tests between the effectiveness of the 6.8mm in comparison with the various 5.56mm loadings, but I would expect it to be considerably more than 20% more effective.
I agree with Jeff that on the basis of information available so far, I would like to see the 6.8mm entirely replace the 5.56mm - in fact, its performance is so close to the 7.62mm that I think it could replace that as well. However, I think that the SF route is its best chance; there are fewer problems in adopting unconventional wapons, and it gives it a chance to prove itself.
With the US Army considering changing to the XM8, and needing to replace the worn-out M249 SAWS, there may never be a better chance to switch calibre.
P.S. I've just spotted a news item on StrategyPage.com concerning the US Army's plans for the XM8. This is an extract:
"Testing will increase, as more M-8s are available, and the plan is that by early 2007, the first of over a million M-8s will begin distribution to all troops in active and reserve army units. One thing that may slow this down is the army research on the use of a new caliber (6.8mm). The new bullet has shown to have better accuracy and stopping power. While troops would be carrying less ammo with the larger round (25 rounds in the current 30 round magazine), they would require fewer shots to take down enemy troops. American troops today are much better trained in the use of their rifles than they were four decades ago. Automatic fire is not often used, with accurate, individual shots being the norm. The M-8 rifle, and possibly a new caliber, are a reflection of that."
Tony Williams: Military gun and ammunition
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