I'm not sure if this goes here but I imagine you guys can tell me what I need to know. So I'm thinking of SBRing my 6.5, what kind of velocities can expect with 130's. It has a 1:8 twist rate is this too tight for 123's, they shoot really tight out at 300 but are over stabilized at 100 and shoot about 2.5". I'm thinking the reduced velocity combined with the tight twist will be just right.

I built a 12.5 inch 6.5mm Grendel AR pistol and have an article on it coming out in G&A Handguns magazine shortly.
I love it, lot of fun.