260 or Creedmore?

[No_Regerts]

If you are spending the money/time on a custom barrel, why not a custom chambering?
260 Ackley might be an option you have not thought of....

I had mine built as a hunting rifle back in the early 2000's with a Lilja barrel 1:8 twist 24" on a Remington Model Seven Action.

It shoots sub half MOA with Nosler 120 Ballistic tips at 3120 FPS. It reaches out there pretty good and lays the smack down nicely.

He is using an AR10 platform. I've never tried an AI in a semi-auto, but I would wonder about reliable feeding a steep shouldered and straight tapered blown out case.

 

[B3dlam]

6.5 Creedmoor hands down I have an AR-10 chambered in 6.5 creed and I LOVE it.
Brass is readily available from multiple makers (lapua will be releasing their brass this quarter as well).
The Creedmoor was designed to reliably feed in a semi-automatic such as the AR-10
The creedmoors case length allows you to get bullets seated to mag length without loosing significant case capacity.

If you have any questions about 6.5 in the gas gun let me know I've run mine for a few years now and have roughly 800~ rounds through it (I'd have to look at my barrel log to be sure).

 

[erslll]

My RPR in 6.5 CM with a Proof Research 24" barrel shoots factory 140 gr ELD-M loads at almost exactly the factory listed speed, according to my chronograph, which is just a little over 2700 fps. My reloads are either 140 ELD-M or 143 ELD-X with 42.5 grains of H4350 and both are at about the same velocity, if not just a little faster (20 fps maybe but I don't remember the exact numbers off the top of my head).

Needless to say, I vote 6.5 Creedmoor also.

 

[stickflickin]

If you are spending the money/time on a custom barrel, why not a custom chambering?
260 Ackley might be an option you have not thought of....

I had mine built as a hunting rifle back in the early 2000's with a Lilja barrel 1:8 twist 24" on a Remington Model Seven Action.

It shoots sub half MOA with Nosler 120 Ballistic tips at 3120 FPS. It reaches out there pretty good and lays the smack down nicely.

I would love to but when I looked into it the consensus was that the steeper shoulder won't feed reliably in the AR platform.

 

[stickflickin]

Or why not build a 308? Honestly, while I was trying to go along with the OP's line of thinking, I'd not build an AR-10 rifle that's less than a 30 cal.

4 reasons - Because I have a 308 AR, a Steyr SSG 69 (308), the 260 or CM ballistics are superior to 308 and I am a perfectionistic nut that is searching for the next best thing to play with

 

[stickflickin]

A 260 will have to be loaded to max available OAL because of the case length. The 6.5 CM, with its shorter case, gives you more latitude. 2.8 with a 260 may not kiss, but 2.8 in a 6.5 CM likely will because more of that 2.8 is exposed bullet.

That is the CM argument exactly. I was hoping for a "magic bullet" answer for the 260. My hangup is the brass that I have. I guess I just need to "bite the bullet", quit being a cheap bubblegum and go with the CM. Sorry for the bad puns

 

[PaulB47]

As to the introduction of cartridges, Hornady did it exactly right, and Remington (with the .260 and others like 6mm Rem) as usual did it wrong. I don't understand why Remington even bothers to introduce calibers any more.

 

[Jamie6.5]

Anybody have good chronograph data on real world 6.5 Creedmoor loads? I have a hard time believing published muzzle velocities on the box of ammo. Barrel length and bullet weights and speeds from ammo shot over a chronograph would be nice to see and compare to my own 260 Rem and 260 Ackley data.....

I am suspicious that the muzzle velocities published for 6.5 CM ammo is "optimistic" or a clever marketing ploy.

Anybody have real world no BS data they would be willing to share?

I don't, but I know someone that does, and have read about others that do, and everyone has been disappointed. Some more than others, but this is the first thread I've read where someone is getting velocities as high as advertised.
This has been especially true with handloads.

But the seating depth issues and corresponding COAL issues for the .260 are real. I have a 6.5X57 Ackley and if I keep 140s in the neck and out of the case they use all the available room in a std long action magazine.