Building an AR308 or 6.5cm

[Red*Lion]

Definitely .308 for a battle rifle.

[vicious_cb]

For a 16-18" barrel .308 all the way. You need a longer barrel to get the optimum burn out of a 6.5 CM.

[JediGuy]

I asked Criterion about barrel length with 6.5CM. I’m paraphrasing, but they felt that you get more out of a short 6.5CM than out of the same length 308. The 6.5CM will gain more from going with a longer barrel than 308 will.

[turnburglar]

My 18" barrel 6.5 creedmoor made the following velocities:

140gr ELDM hornady match: 2633 AVG (.64 G1)

125gr winchester OTM: 2720 AVG

I don't know the G1 for that win OTM, but a 123gr from another company is making .51 G1. Thats equivalent to a 175 SMK, which never meets these speeds even from a 24" barrel. A short barreled 6.5 is equal to or better than a long barreled 308. A longer barrel on the Creedmoor makes it even better. SOCOM is switching out their SR25's from 308 to 6.5. Do you think those guys know what they are doing after 20 years of GWOT?

[JackHass]

LMT MWS uppers can swap barrel calibers easy!

[alcante262]

I went with .308 with 18"barrel and slim line M-Lok handguard.

[Corse]

LMT MWS uppers can swap barrel calibers easy!

Yeah, get both.

[Red*Lion]

I went with .308 with 18"barrel and slim line M-Lok handguard.

You are going to get a longer barrel life out of the .308 as well.

[AndyLate]

You are going to get a longer barrel life out of the .308 as well.

Significantly longer? 6.5 CM is a pretty mild cartridge.

Andy

[99cobra2881]

Barrell life? Yeah I remember that thing I used to worry about back when 6.5 cm ammo didnt require me to get a second mortgage to buy a box of Hornady 147gr. match ammo.

Im not even sure barrel life worries is a thing right now except for the very few very well stocked reloaders. Ive got friends that have powder and primers by the 8lb jugs and 10 thousands but even they are sitting on what they have atm.