Well as the title says, I put the 338 rum through the paces with the 300 gr berger with mixed results. 1st shot was around 700 yards, hit high, then took a poke at 964, high again. WTF My buddy dropped a doe with his 2506 at about 200 and I took off after some rutting bucks. Saw one that seem ok and put the hammer down at 320. He dropped hard and then his head was up and my bolt wouldn't work. Ut oh. I waited and he finally died. I went up to the buck and I hit him through the hind quarters. How the hell did that happen? Quartered him up and went back to camp.Pulled my action out of the stock and the trigger pin that holds the bolt lever had backed out. Repaired and good as new. Monday morning my buddy whacks a nice doe at 400 with the 2506. I finally found another doe and put the hammer down at 550 another miss. I am not happy. Found another doe and pulled the trigger at 300 and oh no, head up again. Another hit in the ass! I went up to 100 yards and dialed the scope down and put the cross hairs on her head and miss high. Next shot miss right, next shot miss right again. Well I wasn't really missing, just missing the neck where I was aiming. The bergers were hitting their mark in the mid section and making a huge mess. Quartered this one out (what was left) and went back and grabbed my 300 rum. Obviously the 338 was off. Went out and found a lone doe on a far hillside dialed in for 600 and gained some confidence back with a clean kill. I went out to the rifle range today and tested the 338 and found it shooting 6 inches right and 3 inches high at my 100 yard zero. I pulled the scope off the rail and checked the screws, all tight. Remounted the scope and retorqued the rings (burris tactical) and torqued the nuts to the rail. I will shoot it again tomorrow. The only thing I can figure is the bouncing of the atv on the rough roads knocked my zero off, but so far no explanation. The bergers seem to kill well with lots of damage and very little bloodshot. My scope is a sightron S*3 8-32x56 and I have had great luck with it tracking well.