6.5CM vs 308

[Pappabear]

Which is more deadly? 6.5CM with 140 grain fodder vs 308 with 168 fodder? Or whatever is a fair comparison. Wonder what Military experts say or ballistic experts say? I'm sure this has been beaten up somewhere but I couldn't find it.

I believe both are great, but is there a winner winner chicken dinner?

I know shot placement is key but other than that..?

PB

[pointblank4445]

Which is more deadly? 6.5CM with 140 grain fodder vs 308 with 168 fodder? Or whatever is a fair comparison. Wonder what Military experts say or ballistic experts say? I'm sure this has been beaten up somewhere but I couldn't find it.

I believe both are great, but is there a winner winner chicken dinner?

I know shot placement is key but other than that..?

PB

HUGE fan of the 6.5CM. Definitely a big believer that the accuracy/external ballistic advantage was worth it. The ballistics experts said nay-nay...terminal ballistics are inferior. OK with only match bullets...I can see that argument.

Enter non-match bullet selection (hunting style...off which several tactical rounds have roots) for the 6.5CM...I think ok NOW the 6.5mm can party but many experts still say nay-nay. I thought this was BS until I started seeing some data on weight retention. While certain 308 rounds (168gr) were retaining say 88-90% weight retention through mediums, the same bullet style in the 6.5CM was only showing about 50% weight retention for an already 30-40 grain lighter bullet (thus only bringing to bear the same bullet weight as a 5.56)

You're still going to see plenty of pull for the 6.5CM as a LR open air round (not unlike a pumped up Mk262) where it's ability to connect is the big factor...and that a less terminal performance hit is better than the more devastating miss. But as far as the performance through barrier stuff...limited data shows the 308 has the advantage coming out the other side. I certainly wouldn't scrap my 6.5 to go back to 308 any time soon, but I'm aware of its disadvantages.

[jack crab]

The numbers for the 6.5CM pull ahead of the .308 starting about 700 yards.

[C-grunt]

From what I was told by a sniper who was there for testing, the 308 had better terminal ballistics at closer ranges. I don't know what the testing involved ( I want to say ballistic gel but I cant remember exactly) and it was a LE test so it only went out to a few hundred yards. He did say they believed the 6.5 would overtake the 308 out past 500 yards or so, but that wasn't actually tested.

[Pappabear]

I don't have a 6.5 hunting gun, but I would use on Whitetail if I did. For Elk, the magnums are by far the winner. Two legged creatures would certainly fall to a 6.5. I can see how that long skinny bullet would not retain as well as the chubby 308 by comparison.

Thanks for the replies, was just curious what the current thought leaders were saying.

PB

[Failure2Stop]

First question is "what barrel length"?
But even then, with all else being equal, when it comes to hunting I favor .308, as I have produced more consistent "on the ground/no-tracking" kills with task-specific .308.
When it comes to taking humans out of the fight, I'm going 6.5.
The first step to good terminal ballistics is getting the projectile into the target, and it's easier to do that in real conditions with 6.5 at distance than it is with .308, all else being as similar as possible. There's a reason we've kept the 5.56 as the primary service cartridge for so long. 6.5 kinda splits that difference, but still suffers from low on-board and on-body ammo capacity. I am a 6.5 fan, but I am realistic about what it is and what it is not.

[PracticalRifleman]

Which is more deadly? 6.5CM with 140 grain fodder vs 308 with 168 fodder? Or whatever is a fair comparison. Wonder what Military experts say or ballistic experts say? I'm sure this has been beaten up somewhere but I couldn't find it.

I believe both are great, but is there a winner winner chicken dinner?

I know shot placement is key but other than that..?

PB

I think there are so many factors to think about here. The 6.5 should be easier to connect with. The .308 retains more weight/momentum. What kind of bullet? What kind of game?

If I’m trying to kill with a 6.5, I’m going to choose 6.5 PRC or 6.5-284.


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[gaijin]

Swedes have used 6.5X55 forever killing Moose.

The hook is (as you said) shot placement and bullet construction.
Pinpoint shot placement is easier with a softer recoiling rifle, so a nod to 6.5.
We Americans are pretty fond of .30 caliber though.

[BufordTJustice]

I built my AR10 in 308 because that’s what I was familiar with. I run Federal LE308TT2 (168gr Trophy Bonded Tip) in both my Tikka Bolt gun and the semi, to great effect. But I only intended it to be a 500</= yard tool.

I haven’t taken it up directly against a 6.5CM during my Florida hog hunts. But, using the above ammo (and a Saker 762), I have had multiple guides think it was a larger cartridge (300 wsm, 30’06, etc) due to how hard it struck those big hogs.... typically flipping the entire animal directly into a DRT nap. So I’ve got no practical reason to change for my use case. I doubt I would feel the need to change if I were using 6.5CM, either.

I would love to build a 6.5CM rig, but just can’t justify the additional cost of the rig, plus ammo right now.

I actually came from the high sectional density crowd, as my first hunting rifle was a Remington 700 in 270 Win. Never had a 300+lb hog move more than a foot with any 130gr bonded/homogenous round I used.

As others have said, bullet construction plays an enormous role.... but also in 308.

Lastly, the 270 made the wind much less of a factor and it just shot flatter. We all know that the 6.5CM significantly outpaces the lowly 270 in every area of precision and is auto loader compatible as well.


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[FightinQ]

I'm already well invested in .308 and and have yet to be disappointed. Plus I don't feel any real change in recoil between the two. Shooting both side by side, it used the same 500 yard hold up to 500 yards, so I saw no valid reason for myself to get on board as .308 has never once stopped working for me. Cheaper ammo, easier to find ammo too if in a pinch, and I've already got the time vetting loads and an a very big ammo pile in the tens of thousands.

I'm not a sniper, so I won't pretend to be one.I don't PRS nor want to. I don't hunt either but that's a personal choice. And neither am I ever planning on taking a .308 or the other to "war" for that matter as well, that's being ridiculous for home defense. For up to 500 yards, .308 never stopped working for terminal effects on humans and with the advantages of better bullet technologies out there, it's still being validated for my intended uses of it.

As for terminal, both will do it just as effectively within reasonable distances to be honest. The rest is just subjective.