Relevance of intermediate rounds such as 6.8 under 'new' paradigm?

[calvin118]

In the older school of thought that favored fragmenting 5.56 rounds for all-purpose defensive loadings, the advantages of calibers such as the 6.8 were concrete and significant.

A) Fragmentation was the key to ideal wounding, and fragmentation range increased dramatically with the larger calibers at a given barrel length.

B) Larger calibers such as 6.8 SPC defeated barriers that OTM and FMJ 5.56 rounds could not.

The new thinking seems to be that barrier blind 5.56 rounds such as BH 50 grain TSX should be employed for general use. They maintain ballistic performance out to 300 yards, which largely negates the range issue. They also defeat commonly encountered barriers, unlike their OTM and FMJ cousins.

If we accept that their terminal performance (expansion to ~.45" and a large, consistent, early-forming temporary cavity that wounds inelastic and fluid filled organs such as the heart, kidneys, and liver) is adequate without fragmentation, is there much of a point to larger calibers such as the 6.8 anymore? Or has this become more of a marginal, incremental paradigm such as the 9mm vs. .40 S&W vs. .45 ACP?

[C-grunt]

Hmm. Interesting theory. Id be inclined to believe that with good barrier blind loads that the slightly larger intermediate sized cartridges dont offer much over the 5.56.

[DocGKR]

Intermediate calibers (6.5-7mm) with well designed barrier blind loads are substantially MORE impressive than any 5.56 mm load...

[200RNL]

Intermediate calibers (6.5-7mm) with well designed barrier blind loads are substantially MORE impressive than any 5.56 mm load...

Is the siren song of the 7.62x51 again beckoning? I'm getting another headache.

[caporider]

Is the siren song of the 7.62x51 again beckoning? I'm getting another headache.

Intermediate calibers that fit the AR15 magwell do not exact the carry weight penalty of .308 ammo (not even close) and obviously do not need the heavier and larger AR10/SR25 platform.

[Jack-O]

Intermediate calibers that fit the AR15 magwell do not exact the carry weight penalty of .308 ammo (not even close) and obviously do not need the heavier and larger AR10/SR25 platform.

+1

dont forget that the 6.8 also has extended the effective range of the carbine as well as the terminal ballistics.

better 5.56 bullets are really just a patch for it's inherent deficiencies. It works, but it's still subject to the laws of physics and momentum. Heavier, still breaks thru stuff better.

[Microalign]

I've been debating this myself. By all means of measurement, ie terminal effects and barrier testing, the 6.8 is superior to the 5.56 in every way, and is a much more manageable carbine choice over the .308. It is just unfortunately that the 6.8 lacks any wide spread adoption. I would also like to see a lower receiver specifically designed for the 6.8 so that the magazine well can be wider and accomidate magazines on par with PMAGs instead of the thin steel walled magazines available now.

[bernieb90]

+1

dont forget that the 6.8 also has extended the effective range of the carbine as well as the terminal ballistics.

better 5.56 bullets are really just a patch for it's inherent deficiencies. It works, but it's still subject to the laws of physics and momentum. Heavier, still breaks thru stuff better.

Lets not forget that the 6.8 is in itself a patch which operates within the limitations of the AR-15 platform. If we had something like an AR-12.5 that provided a longer magazine well, and action than the AR-15, but still shorter than the AR-10 we could start getting rifles that are optimized for the 7 X 46mm and other true intermediate cartridges.

Considering all the gear many people hang off an AR-15 a naked AR-10 like a Larue PredatAR .308 doesn't really weigh any more. As far as ammunition goes I don't see ammo weight being an issue for civilian or even LE tactical usage. The tradeoff between firepower, and mobility is always a consideration. .308 still holds a significant advantage over any of the other common service rifle calibers as far as terminal performance, and intermediate barrier performance. The user must of course determine if the added recoil, weight, and expense is worth the increase.

[DocGKR]

Gee...which one is likely to be more effective at incapacitating an aggressive violent opponent?

[Clint]

Intermediate calibers (6.5-7mm) with well designed barrier blind loads are substantially MORE impressive than any 5.56 mm load...

This is also backed up by TONS of non-scientific real use evidence as well.

Chris L (HTR) has taken over 400 hogs with nearly every available combination of loads in both 5.56 and 6.8.

Hogs are tough. They are practically a walking barrier of bone and mean.

His summary is that the 5.56 would drop them with a single shot around half the time.

In other words, inconsistent terminal performance.

With the 6.8, single shot drops are closer to 9 out of 10.