16” 6.5 Creedmoor barrel worth it?

[markm]

I hypothesize that the 6mm ARC has the same problems that other cartridges before it have suffered.
1) much hype, big fanfare
2) handloaders attempt to reproduce the hype, because without the advertised numbers, the cartridge doesn’t make much more sense than existing ones.
3) everyone discovers that physics still exist.

Outstanding post. Much more elegantly put than how I usually just call stupid cartridges "retarded".

[pointblank4445]

1) much hype

This is the enemy of every new cartridge.

People were expecting scaled down 6.5CM ballistics down to a 16-18" small-frame AR15 with the 6ARC. Meanwhile you see hype of the 6.5CM being hyped as having a ballistic arc/trajectory to .300WM. We've already seen in this thread the inevitable 6.5G to 6.5CM comparison cause "It's all 6.5mm"...about like a Frenchie and a pitbull are comparable as "terriers".

People always gettin' set up for disappointment making comparisons outside of a straight "apples-to-apples":
A) Cartridge type (magnum vs. short action rifle, intermediate vs. short action rifle, etc.)
B) Platform type (large frame vs small frame vs bolt)
C) Barrel length inconsistency

Ya know what ya don't see much of:
- Here's what a 6ARC is doing out of an 18" AR compared to 77smk out of an 18" AR
- Here's what a 6.5CM is doing out of a 16" SR compared to a 16" 308 SR


For the record, I think there's a better mousetrap to be had in a 6mm AR15...

[Disciple]

Sheared lugs, broken extractors and all the other fun stuff trying to trim off the meat to accept 220 Russian bases into an AR bolt.

That technology was already worked out with the 6.5 Grendel. Use good bolts and don't handload using pressure signs as your guide (which appear much higher than 52,000 PSI) and the problems go away, unless I am badly misinformed.

We've already seen in this thread the inevitable 6.5G to 6.5CM comparison cause "It's all 6.5mm"...about like a Frenchie and a pitbull are comparable as "terriers".

I feel personally called out here, and if so I am being misrepresented. My point was that heavier bullets appear to provide a greater relative benefit from the Creedmoor.

[pointblank4445]

Point noted with the PSI, but tis the nature of the beast to want more and push a bit more, and a bit more. Again, people experimenting to make things what they aren't.

I feel personally called out here, and if so I am being misrepresented. My point was that heavier bullets appear to provide a greater relative benefit from the Creedmoor.

Not a call-out, more just springboarding off that comparison and poking fun at the startling amount of people that put too much stock into bore diameter, and not enough into case capacity and the relationship of BC to MV.

Honestly, I and others have circled the question of short/handy and its relation to performance/capability. I can fill an album with my failed endeavors in this area. It always reminds me of what I call the "CCW Paradox" which is just the boiling frog in gun terms. If y'all will indulge me, it starts like this:

- I should get a Glock 43 to carry
- Perhaps it should be a 43X for capacity
- If I'm going to 43X, might as well G48 since I AWB since the grip size is no different
- If I'm G48, I might as well G19 since it's the same footprint but with better performance capacity
- If I'm G19, what's a fraction of an inch on the grip and barrel to go G17
- Since I got a G17 sized grip might as well just roll G34 and slap on an X300.

Between each step is small but top and bottom are miles apart. Figuring out the nuance of that sweet spot FOR YOU is the hard part.

[markm]

It always reminds me of what I call the "CCW Paradox" which is just the boiling frog in gun terms. If y'all will indulge me, it starts like this:

- I should get a Glock 43 to carry
- Perhaps it should be a 43X for capacity
- If I'm going to 43X, might as well G48 since I AWB since the grip size is no different
- If I'm G48, I might as well G19 since it's the same footprint but with better performance capacity
- If I'm G19, what's a fraction of an inch on the grip and barrel to go G17
- Since I got a G17 sized grip might as well just roll G34 and slap on an X300.

Between each step is small but top and bottom are miles apart. Figuring out the nuance of that sweet spot FOR YOU is the hard part.

I see the same paradox in REVERSE with rifles all the time on the forums. This thread topic is a world class example.

Now I'm not totally unsold on the possibility of the OPs idea, but it is the classic example of wanting big performance in a smaller and/or lighter package.

[constructor]

This is the enemy of every new cartridge.

People were expecting scaled down 6.5CM ballistics down to a 16-18" small-frame AR15 with the 6ARC. Meanwhile you see hype of the 6.5CM being hyped as having a ballistic arc/trajectory to .300WM. We've already seen in this thread the inevitable 6.5G to 6.5CM comparison cause "It's all 6.5mm"...about like a Frenchie and a pitbull are comparable as "terriers".

People always gettin' set up for disappointment making comparisons outside of a straight "apples-to-apples":
A) Cartridge type (magnum vs. short action rifle, intermediate vs. short action rifle, etc.)
B) Platform type (large frame vs small frame vs bolt)
C) Barrel length inconsistency

Ya know what ya don't see much of:
- Here's what a 6ARC is doing out of an 18" AR compared to 77smk out of an 18" AR
- Here's what a 6.5CM is doing out of a 16" SR compared to a 16" 308 SR


For the record, I think there's a better mousetrap to be had in a 6mm AR15...

Agree, Hornady chose the wrong case for an AR15 and they had both examples at the same time when they were making my custom dies a year before they decided to make the 6mm ARC. The 6.8 case would have been better, we have 30 round pmags that function perfectly, bolts don't break as easy and we can run 58,000 psi with no issues.

[constructor]

10-12 years ago on the military arms and ammo forum we were talking about a true mid sized cartridge and what would be most efficient for military use with shorter barrels. Cris Murray was working on a new machine gun cartridge that would reduce the size and weight of the 240. He had it right, a cartridge of 42-45gr H2o capacity is about perfect for barrels 14-18" long. His 7mmUIAC cartridge would have worked but to realize the benefits they would have needed to make a new rifle platform between the AR15 and AR10. That would handle cartridges 2.6" long and a bolt and BCG not as large as the AR10 but larger than the AR15. .050" larger in dia than the AR15 would have been enough. I machined 10 bolts so he could test his 7mm UIAC in a MG42 he converted. The case is the diameter of a Carcano, just a little larger dia than the Grendel but longer.
Cases larger than that are blowing powder out the end of a 16" barrel, cartridges smaller just can't push the bullets fast enough without excessive pressure.

[markm]

to realize the benefits they would have needed to make a new rifle platform between the AR15 and AR10. That would handle cartridges 2.6" long and a bolt and BCG not as large as the AR10 but larger than the AR15. .050" larger in dia than the AR15 would have been enough. I machined 10 bolts so he could test his 7mm UIAC in a MG42 he converted. The case is the diameter of a Carcano, just a little larger dia than the Grendel but longer.
Cases larger than that are blowing powder out the end of a 16" barrel, cartridges smaller just can't push the bullets fast enough without excessive pressure.

Yeah. I remember an instructor talking about this a long time ago. They need to make an "AR-12" was sort of his point that goes along with your point.

[1168]

Geissele wouldn't have jumped into the game if there wasn't DOD money to be gained from it.

Unless of course they thought there was money to be gained by association of their name with DoD.

[drtywk]

Unless of course they thought there was money to be gained by association of their name with DoD.

Hence my entire point. G would not have jumped into this, or their 6.5CM project (MRGG), if there wasn't DOD funding involved in the development, which would also lead to the potential of the "me too" buyers out there helping them recoup their cost sharing portion of the project.