Sorry Randy you can't use a 6.5 creedmoor upper on an AR15 lower. The creedmoor AR is based on the AR10 platform which is chambered for the 308 winchester. The AR15 platform can be had in a wide variety of chamberings but is limited to cartridges with a maximum overall length of 44.70 mm .
Can you put a 6.5 upper on a ar15 lower?
Q: So, can I just install a Grendel upper on my 5.56 or . 223 lower? A: Yes, if you already own an AR-15 chambered in 5.56 or that uses a standard lower receiver assembly for another cartridge, you can buy a 6.5 Grendel upper and install it on your lower.10 ago 2020
What is the best barrel length for 6.5 Creedmoor in the AR platform?
The consensus on the optimal barrel length for 6.5 Creedmoor is 24” and 26”, if the objective is long range Precision Rifle Shooting (PRS). The reason for this is to generate the highest muzzle velocities, and lowest Standard Deviation of velocity.
What is the best barrel length for AR-10?
Number-1 - It light and easy to carry. Number-2 - The AR and its ammo is really designed around a 16″ barrel. The 1:9 twist gives the best general performance with light and heavy bullet weights.
Is 18 inches too short for 6.5 Creedmoor?
Some will argue that 18” is too short for the 6.5CM, but if you figure 20-25fps per inch of barrel reduction, you can do the math there. I think you'll be fine. Suppressed will be even better.25 feb 2020