For sure. I'm going to pick up a Forster Co-Ax press for this one. My Dillon 550 is great for most things I'd ever want to use it for, but the Forster gives you total control over every aspect of the load.
Flatter shooting at pretty much any distance and less wind deflection and it retains more energy. There are a bunch of charts towards the bottom of this page: http://www.65grendel.com/faq.htm
And here's a PDF I came across a while back that gives a quick comparison of external ballistics between a 5.56, .308, 6.8 and a few Grendel loads. http://shootersforum.com/attachment.htm?attachmentid=446&d=1076081272
Re: 6.8 question, remember that the 6.8 was designed for the 300 yard world, while the 6.5 was designed to be in a way the 'ultimate' all around round that would fit into the AR-15 magwell. Load up 144s for nice long range shots, some 90s for varminting, and some 123SMKs for CQB. I mean, 6.8 is nice and all, and has some big names and fancy advertising, but its designed for REALLY close in work, and only has one grain choice for weight. 6.5 might not be *quite* as good if you're really close in, but its far more adaptable.
I'm going to take a shot at doing it myself. We'll see how well it shoots. i ordered the 24" barrel and bolt from AA this morning. I'm thinking about a JP handguard and maybe a billet upper. So far that's all I've thought up. If anyone has any suggestions I'd love to hear them.
While you're spending $$, I wouldn't mind about 50 feet of 3/8" copper tubing http://www.coppertubingsales.com/copper_tubing_prices.php
What if there's 2 people and one needs to shoot the close zombies and one needs to shoot the far zombies? duh!
He has a completed .223 one, the lower that he's turning in to the grendel, and I have my lower that I don't know what I'm going to do with yet.