Dawaba,
As you said it is an excellent movie, with some awesome shots. The rig John Burns is using is a modified 7mm, there it some info on his website about the gun although it doesnt go into much detail. An outfitter I have personally hunted with is on there, John Porter of Morning Creek Outfitters. He is a great guide in those mountains NW of Cody, and an even better shot. The last hunt I was on with him, my dad shot a cow elk @ 868yds, another fellow @ 767yds, and myself(young pup at the time) 350 yds. Last year my dad was out there with his brother when he shot one at 1002 yds. It's crazy but with the right equipment, knowledge and practice all this is possible. My dad is heading back out in December with them again, I'll keep you posted. I know they're planning to try some more 1k shots.
BTW the new video is out but pretty $$$ it deals more with equipment and technique and so on, so save some up and get it when you can. Good Luck!