Stag, by "performance" you are speaking of velocity I'd assume.
Is that so?
I have many notes on both of my 6.8s. My 20" rifle gives me about 150 FPS more velocity with the same ammo as my 16" carbine does. So I would say you are correct if "performance" = speed in your estimation.
But my builds of 6.8s with longer barrels then 20" show me that it's about maxed out at 20". I have made two 6.8 SPCs in 24" and found no gain in velocity to speak of over the 20".
No so the Grendel. You gain a little usable velocity up to about 24" with the 6.5. It just keep getting faster.
I have made a number of 6.5s, and chronographed them from 16" 18" 20" and 24" barrels and I have found the Grendel is a "rifle shell" more so then the 6.8.
The comparison of the 6.8 and the 6.5 in 16" barrels makes me like the 6.8 a bit more. Not just the numbers, but the kills I have made and seen made.
The gains you get from the Grendel over the 6.8 are really only realized when you compare the 6.5 to the 6.8 in 20" and longer barrels.
In side by side tests with top loads in the 6.5 and the 6.8, in 16" carbines I found the Grendel doesn't do any better at the muzzle then the 6.8 and in 2 cases it was actually a little slower. About 45 FPS. Not enough to impress me at all, but enough to prove to me the 6.8 is NOT inferior to the 6.5 in the short barreled carbines.
Now that's not to to say the 6.5 bullet would not out-fly the 6.8 at range.
It does.
I have made them both, used them both and as a full time gunsmith I can have either one for exactly the same effort and the same cost.
I do not own a Grendel myself now.
Why?
The 6.8 has been more effective for me when killing game than the 6.5 Grendel in the 16 and 18" length barrels. I attribute the difference more to the bullets used in the 6.8 being a bit better overall then the 6.5 bullets for HUNTING. Bullet companies are paying attention today more then they were 10-15 years ago, so that gap is closing a bit.
The 125 grain Nosler Partitions in .264 closes the gap a lot, but are a bit expensive.
The .277 bullets I have used so far on my 34 head of game have all exited except for one. So I have near perfect penetration from the .277' bullets and the wound channels are notable bigger in diameter then those I have seen from the 6.5s
This is pretty typical.
I have no doubt that the 6.5 would do the same damage at longer range and surpass my 6.8s, but so far I have not seen that theory bear out.
So far I have not killed anything, or seen anything killed with the 6.5 Grendel beyond 265 yards. Up to 200 yards I expect a better result with the .277 bullets then with the .264 bullets, and so it has been, but I have only seen about 14 animals killed with the Grrendel so far, compared to a total of 106 killed by 6.8SPCs, killed by my friends and myself combined.
So the deck may be loaded unfairly in that comparison. Time will tell.
The 16" carbines are more popular not because of velocity, ("performance") but because of their compact size and fast handling. The real truth of the matter is that by FAR, most kills on deer and even antelope are at 300 yards and less, and probably 75% of them are a lot less.
From the muzzle to 200 yards, I have found the 6.8 drops deer and antelope a bit better than the 6.5 does, and the 6.8 is not giving up anything meaningful in the short barrel to the 6.5. That is to take nothign away from the 6.5. It's a very good way to go. But for me, when I want something that reaches out past 300 yards with no problem, I take my 270 Winchesters, my 25-06, my 30-06s my 8X57 my 308s or my 300 H&H.
It's interesting to point out that my 19" barreled 30-06 firing a 150 gr bullet shoots very well at longer ranges and weight only 7.2 pound scoped and loaded. Lighter than any 6.5 Grendel I have made or seen made with their 20" or 24' barrels. And WAY more powerful. Some people call power "performance" too.
In my way of thinking, I am not trying to compete the 6.5 to the 6.8. I compare the ballistics of the 6.8 to the 1955 era 257 Roberts. This with a shorter carbine instead of the 22" barreled Mausers and Remintgtons most of the Roberts were made from. No one that had any experience with the Roberts ever said it was a bad deer round. It fired 117 gr bullet from a 22" barrel at 2620 FPS. My 6.8 fires a 110 grain bullet from a 16" barrel at 2650 FPS. 7 grains less lead at 30 FPS faster. Close enough to call them the same.
I see the 6.5 as probably the best all around" AR15 round you can get
if you were to only own an AR and no other rifle. It's nearly as effective as the 6.8 out to 200, about the same from 200 to 300 and I have no doubt it will pass the 6.8 at 350+.
But I do have other rifles.
Most with barrels from 20"-24" and nearly all lighter than the 6.5 Grendel rifles with 20 to 24 inch barrels. Most of the 24" Grendels weigh about 10.2 pounds scoped and loaded. My 25-06 has a 25" barrel and weighs only 7.1 pounds.
120 grain bullet at 3000 FPS
I wanted an AR that killed very well, (it does) and was effective to the normal ranges I shoot deer and antelope, and having owned and made both the 6.5s and the 6.8s, I gave up the 6.5 for long range and went back to a bolt action in 270 Winchester. If I am going to carry a 10 pound rifle with a long barrel, I can't see where the 6.5 Grendel did anything for me as well as the 270 Winchester.
That doesn't make me "right" and someone else "wrong". It's just how things fell together in my world.
To me "performance" is more about how well I can shoot a rifle than how well the rifles shoots by itself. I focus more on the "user friendliness" of the rifle than I do it's speed.
