Barrel Nut Rod

[jurassic]

As I'm still building my first Grendel, and the brown Santa hasn't delivered my barrel yet, I have a question regarding the barrel nut: is it the same dimensions as a regular 5.56 barrel nut? the reason I ask is, there is a tool much like the Geissele Reaction Rod that Brownells sells, but is $38 instead of $100.

I have the version from Geissele, the big difference is the length and the flats machined on it at one end. It allows you to clamp the rod into a vice, and it works fantastic! Expensive, but worth every penny. No receiver clamps of any kind needed.