Looks like free-floating the barrel did the trick. It was 26 degrees at the range this morning with no wind. The cold weather really helped cool my barrel and I was able to shoot much faster. I used my IR temp sensor to monitor the barrel temps throughout the shooting session. My best group came from a load of 44gr. of IMR-4064 topped with a Hornady 140gr. SST. I'm getting 1/2" groups at 100 yards! (see pic below)

I also couldn't resist bringing the newest toy to the party, my Smith & Wesson M&P-15.
It's now shooting 2-1/2" groups (or better) at 100 yds with a battle-sight!

Heading out to the range!

I think I found the problem with the Remington 700 (264 WM). Apparently Remington in their infinite wisdom puts a pressure pad about 2" back of the forend tip. This places upward pressure on the barrel. I believe this could be causing the wood stock to change as the barrel heats up. As you can see in the pic, I sanded off the pad and can now pass a dollar bill (or two) completely under the barrel all the way to the recoil lug.  I will be heading to the range tomorrow if the weather holds to test my theory.  

We hit the rifle range today. It was a bit cold but I needed to test out some new loads I worked up. The .300 Win. Mag. shot great as always, but the problem child (my .264 Win. Mag.) was a bit of a disappointment. Although It shot a decent group at 100 yds, I was hoping for better, and as usual, as the barrel heats up the shots start to string out. This doesn't effect hunting situations where normally one shot is taken, but it drives me crazy at the range.

The completed set of new loads for the .264 Win. Mag. Almost to pretty to shoot!

Started working up some loads for the .264 Win. Mag. Hopefully I'll be able to get out to the range this weekend and do a little testing.

I guess I need to start thinking about what weapon to use, bow or gun? (or both?)
My hunting buddy just returned from the same place we are going to and pretty much stated that there's no chance in hell of getting a bow shot in this area. I'm still considering taking it anyways. The one thing I don't want  to do is sit and roast in a pit blind all day watching a waterhole with bugs and snakes crawling in (I hate snakes)
I would rather see the African bush and take in all the sights and sounds. I will bring my trusty Ruger M-77 chambered for .300 Win mag. I have a great load that I've been working up for it and Africa will be the testing grounds. I'm also considering a second rifle as a back-up (a Remington 700 Classic chambered for .264 Win mag) If I forgo the second rifle I can fit my bow into the double gun case.