For a hunting only rifle is there any reason to go with the Predator vs. the Compact? They both look threaded, the predator is a 22" barrel and 6.6lbs, the compact is a 20" barrel and 6.1lbs. I plan on replacing the stock with a B&C or Magpul.

It looks like the B&C stock wont let me use AI mags but I'm not sure it's that big of a deal for a hunting rifle.

If you are replacing the stock anyways, it really comes down to barrel length/velocity loss and whether or not that is important to you.  I have a 6.5 Creedmoor semi-auto that has a 20" barrel that will still shoot 1000 yd no problem, the 147gr ELD-M is still above trans-sonic at 1200 yd.  For a strictly hunting gun, 20" would be PLENTY.  I bought the Predator 6.5 Creedmoor because I wanted AI mag compatibility, didn't want the shorter length of pull, and don't plan on changing out the stock.  Solid, repeatable 0.75 MOA w/ Hornady 140gr American Gunner.

I agree, the 20" should be plenty for hunting distances and save a little weight in the process.

I see Ruger has a stainless 6.5C now in the Predator line so that is tempting as well.

I just ordered the Predator with the AI mags for my son for Christmas for his primary hunting Rifle.  I wanted the AI mags because I don't like the Ruger designed mags in the Ranch Rifle in .300 BLK that we have.

Now I'm waiting on a black Friday deal for a Vortex scope

ETA, the 20" will be fine for hunting