Grendel upper?

[Clod Stomper]

Ok...I am feeling a bit combative today.... I would be willing to bet that a .223 case necked up to 6.5mm would give about the same performance out of a 14" barrel as a 6.5 Grendel out of a 14" barrel. Sure you can shoot a 5.56 out of a 7.5" pistol build, but most of the energy of the 5.56 is not being used because either the powder is not being burned inside of the barrel (excessive muzzle flash) or the bullet exits the barrel before the pressure is able to accelerate the bullet the its potential velocity for a given load.

If you are shooting factory Grendel loads out of a short barrel you are not getting the performance that the Grendel can deliver. There are reasons for using short barrels and having a rifle that uses the same cartridge as the guys in your unit is a big plus. Bolting a high performance motor in a Ford Pinto does not do justice to the high performance motor and does not give you a Nascar. If you want to build a short barrel rifle, choose something that is designed to work with a short barrel. The Grendel velocity numbers are what they are because of a 24" barrel. The compromise is somewhere between 19" & 20" for weight vs. velocity. If you looked at the velocity numbers for the Grendel with a 14" barrel and a 120 grain bullet, you would probably not be impressed.

I think there is something to this. Check out this wildcat: http://www.ar15armory.com/forums/65mm-Pa...95187.html

I don't think anyone has checked velocity of that round from a shorter barrel yet, but I'm guessing that in a shorter barrel, the 5.56 case based round is more efficient. Not that one can achieve MORE velocity, but similar velocities. Of course, in a longer barrel, or with heavier bullets, the Grendel is going to win out.

I had been considering building either a lightweight pistol upper or 14.5" with a pinned flash suppressor in the PCC round primarily because of better efficiency in short barrels (plus being able to use 5.56 brass and magazines).

I have since shelved that idea in favor of the 7.62x40 Wilson Tactical. No point wasting 6.5 BCs in a short range firearm.

I have only fired a Grendel from 28", 18.5", 18" and 16" barrels. So far, my preferred barrel length is 18" to 18.5". The muzzle blast from the 16 is noticeably sharper than from the 18. To my ears at least. Of course, the 28" was just horribly unwieldy and didn't have enough increased velocity to justify the extra length and weight.

Will