12-31-2014, 09:48 PM
I have had two .260 Remington AR10's, and currently own the later one, built by GA Precision with a Bartlein barrel. I have many friends with .260's and 6.5 CM's, as well as 6.5x47 Lapua's (in bolt guns mostly).
.260 Remington Pro's:
* More factory brass availability
* brass is thicker
* More case capacity
* Same shoulder angle and location as .308, works very well from mags meant for the large AR's
6.5 Creedmoor Pro's
* 30 degree shoulder burns efficiently
* Load recipe printed on Hornady factory ammo boxes
* Good barrel life
* Hornady is doing a lot to support the cartridge
Con's for both:
These are basically hand-loader's cartridges only in the gas guns, unless you shoot the 120gr hunting or lighter loads. Once you get into target pills of 123gr and higher, the slow-burning powders hit the gas port much harder, and violently drive the bolt carrier to the rear, when the case is still obturated in the chamber. To mitigate that, I use H4350 under 129gr and 130gr pills, to achieve fast enough muzzle velocity to make it worth it.
The 6.5 Creedmoor brass is actually quite thin, which doesn't bode well for brass life. I think Hornady really pushed the edge to be competitive with the .260 Remington, and in order to make up for loss of case capacity by using the 30 TC parent case, they thinned the walls.
The .260 Remington, especially the Lapua brass, has very thick case walls, which deal with a gas gun cycling much better, and helps with bra$$ life.
One problem for you will be with your existing .308 brass, in that you will have to trim the diameter and uniform all your necks, as the sizing process will accumulate the mass so that the necks are too thick to load and chamber after the bullet is seated.
With either of them, you will need to pay close attention to your neck lengths, and trim and uniform as they grow. My .260 Rem sees a lot of neck growth with these high pressures, so reloading for it is a pain if you're not set up already. Failure to uniform the necks spreads the ES all over the place.
For your recoil system, seriously look at getting the JP AR10 SCS if you decide to move forward with this. The main advantage the 6.5-08 variants have is being able to duplicate 300 WinMag trajectory, with less recoil than a .308, with energy like a .30-06 from about 275yds on out.
.260 Remington Pro's:
* More factory brass availability
* brass is thicker
* More case capacity
* Same shoulder angle and location as .308, works very well from mags meant for the large AR's
6.5 Creedmoor Pro's
* 30 degree shoulder burns efficiently
* Load recipe printed on Hornady factory ammo boxes
* Good barrel life
* Hornady is doing a lot to support the cartridge
Con's for both:
These are basically hand-loader's cartridges only in the gas guns, unless you shoot the 120gr hunting or lighter loads. Once you get into target pills of 123gr and higher, the slow-burning powders hit the gas port much harder, and violently drive the bolt carrier to the rear, when the case is still obturated in the chamber. To mitigate that, I use H4350 under 129gr and 130gr pills, to achieve fast enough muzzle velocity to make it worth it.
The 6.5 Creedmoor brass is actually quite thin, which doesn't bode well for brass life. I think Hornady really pushed the edge to be competitive with the .260 Remington, and in order to make up for loss of case capacity by using the 30 TC parent case, they thinned the walls.
The .260 Remington, especially the Lapua brass, has very thick case walls, which deal with a gas gun cycling much better, and helps with bra$$ life.
One problem for you will be with your existing .308 brass, in that you will have to trim the diameter and uniform all your necks, as the sizing process will accumulate the mass so that the necks are too thick to load and chamber after the bullet is seated.
With either of them, you will need to pay close attention to your neck lengths, and trim and uniform as they grow. My .260 Rem sees a lot of neck growth with these high pressures, so reloading for it is a pain if you're not set up already. Failure to uniform the necks spreads the ES all over the place.
For your recoil system, seriously look at getting the JP AR10 SCS if you decide to move forward with this. The main advantage the 6.5-08 variants have is being able to duplicate 300 WinMag trajectory, with less recoil than a .308, with energy like a .30-06 from about 275yds on out.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com