Not to "Pick a fight" with VA BigBore... ;D......but I'm gonna disagree on the Grendel not being a viable deer cartridge past 200 yards. If you look at the ballistics as posted on Hornady's web site
http://www.hornady.com/store/6.5-Grendel-123-gr-A-MAX/ the 6.5 bullet is pushing out almost 1200-ft\lbs of energy at 300 yards and even at 400 yards you have just over 1000-ft\lbs of energy. The 400 yard shot would be pushing it on a big heavy whitetail.
I'm a die hard fan of the 6.5 Swede and the only thing I think the Grendel can't do is push a heavy 140gr. bullet well. However, the "rule of thumb" is that it takes 1000-ft\lbs of energy for a bullet to do a quality job of killing a whitetail. So, I would have no problems shooting the Grendel as long as I'm getting those kind of velocities.
Now, it may be that VA Bigbore is not getting that from the short barrel pistol. In that case, the Grendel may be limited to a shorter distances, and if you look at the Hornady data when it's shot from a 16" barrel, that shows it. On a large whitetail 300 yards may be a push.
I know that when I take my 7-30 Waters Encore Pistol out, I set up so my shots are no longer than 200 yards. That way there is no temptation to wound one.
But with a rifle, I think 300 yards would be a good rule of thumb with the Grendel. And here in Pa., heck....a 400 yard shot is almost unheard of. You will hit a hill before you get a shot that long!!!!
DAve